rooting out old Python dependencies

[Robert Huff]

Hello:
	I recently made an effort to move all ports from 2.7 and 3.7 to
3.9.
	And I though I had succeeded ... until I ran into this while
rebuilding harfbuzz:

===>  Building for harfbuzz-2.8.1
[ 10% 1/10] /usr/local/bin/meson --internal exe --capture src/hb-gobject-enums-tmp.h -- /usr/local/bin/glib-mkenums --identifier-prefix hb_ --symbol-prefix hb_gobject --template /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/src/hb-gobject-enums-tmp.h.tmpl /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-aat-layout.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-aat.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-blob.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-buffer.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-common.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-deprecated.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-draw.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-face.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-font.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-map.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-color.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-deprecated.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-font.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-layout.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-math.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-meta.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-metrics.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-name.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-shape.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-var.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-set.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-shape-plan.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-shape.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-style.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-unicode.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/src/hb-version.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ft.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-graphite2.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-glib.h
FAILED: src/hb-gobject-enums-tmp.h 
/usr/local/bin/meson --internal exe --capture src/hb-gobject-enums-tmp.h -- /usr/local/bin/glib-mkenums --identifier-prefix hb_ --symbol-prefix hb_gobject --template /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/src/hb-gobject-enums-tmp.h.tmpl /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-aat-layout.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-aat.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-blob.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-buffer.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-common.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-deprecated.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-draw.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-face.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-font.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-map.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-color.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-deprecated.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-font.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-layout.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-math.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-meta.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-metrics.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-name.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-shape.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot-var.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ot.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-set.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-shape-plan.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-shape.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-style.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-unicode.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/src/hb-version.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-ft.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-graphite2.h /data/port-work/usr/ports/print/harfbuzz/work/harfbuzz-2.8.1/_build/../src/hb-glib.h
--- stderr ---
env: /usr/local/bin/python3.7: No such file or directory

ninja: build stopped: subcommand failed.
*** Error code 1

	This has also happened with rebuilding a couple of other ports.
	What is the correct way to fix this?  And is there a way to go
looking for such cases before they find me?
	(make.conf is appended)


			Respectfully,


				Robert "not a Python guru" Huff


#WITH_DEBUG=yes

SENDMAIL_CFLAGS=-I/usr/local/include/sasl -DSASL
SENDMAIL_LDFLAGS=-L/usr/local/lib
SENDMAIL_LDADD=-lsasl2

#DEFAULT_VERSIONS+=linux=c6_64 samba=4.4 python=3.5 python3=3.5
DEFAULT_VERSIONS+=linux=c7 samba=4.10

# Possible values: 2.7, 3.4, 3.5, 3.6
DEFAULT_VERSIONS+=python=3.9

# Possible values: 2.7
#DEFAULT_VERSIONS+=python2=2.7

# Possible values: 3.4, 3.5, 3.6
DEFAULT_VERSIONS+=python3=3.9

DEFAULT_VERSIONS+=perl5=5.32

DEFAULT_VERSIONS+=php=7.4

DEFAULT_VERSIONS+=java=14

DEFAULT_VERSIONS+=samba=4.13

DEFAULT_VERSIONS+=llvm=11

WITH_CCACHE_BUILD=yes
CCACHE_DIR=/data/ccache