Mixed signals for graphics/librsvg2-rust on RPi4

A recent attempt to compile gimp under poudriere stopped, reporting 
a failure to build graphics/librsvg2-rust. The offending directory 
was deleted then restored using git restore graphics/librsvg2-rust 
and the build of gimp attempted again.

The build ended with status done, but graphics/librsvg2-rust is still
reported as failed. The log ends with

libtool: link: cc -o /wrkdirs/usr/ports/graphics/librsvg2-rust/work/librsvg-2.50.3/tmp-introspectavpjcero/.libs/Rsvg-2.0 -I/usr/local/include -O2 -pipe -fstack-protector-strong -fno-strict-aliasing /wrkdirs/usr/ports/graphics/librsvg2-rust/work/librsvg-2.50.3/tmp-introspectavpjcero/Rsvg-2.0.o -Wl,--export-dynamic -pthread -fstack-protector-strong -Wl,--export-dynamic  -L. ./.libs/librsvg-2.so -L/usr/local/lib -lgmodule-2.0 -lpng16 -lz -lcairo-gobject -lgdk_pixbuf-2.0 -lgio-2.0 -lxml2 -lpangocairo-1.0 -lcairo -lpthread -lpangoft2-1.0 -lpango-1.0 -lgobject-2.0 -lglib-2.0 -lintl -lharfbuzz -lfontconfig -lfreetype -lm -pthread -Wl,-rpath -Wl,/usr/local/lib
ld: error: ./.libs/librsvg-2.so: undefined reference to getauxval [--no-allow-shlib-undefined]
cc: error: linker command failed with exit code 1 (use -v to see invocation)
linking of temporary binary failed: Command '['/bin/sh', './libtool', '--mode=link', '--tag=CC', 'cc', '-o', '/wrkdirs/usr/ports/graphics/librsvg2-rust/work/librsvg-2.50.3/tmp-introspectavpjcero/Rsvg-2.0', '-export-dynamic', '-I/usr/local/include', '-O2', '-pipe', '-fstack-protector-strong', '-fno-strict-aliasing', '/wrkdirs/usr/ports/graphics/librsvg2-rust/work/librsvg-2.50.3/tmp-introspectavpjcero/Rsvg-2.0.o', '-L.', 'librsvg-2.la', '-L/usr/local/lib', '-lgio-2.0', '-Wl,--export-dynamic', '-lgmodule-2.0', '-pthread', '-lglib-2.0', '-lpango-1.0', '-lgobject-2.0', '-lglib-2.0', '-lintl', '-lharfbuzz', '-lxml2', '-fstack-protector-strong']' returned non-zero exit status 1.
gmake[3]: *** [/usr/local/share/gobject-introspection-1.0/Makefile.introspection:156: Rsvg-2.0.gir] Error 1
gmake[3]: Leaving directory '/wrkdirs/usr/ports/graphics/librsvg2-rust/work/librsvg-2.50.3'
gmake[2]: *** [Makefile:1274: all-recursive] Error 1
gmake[2]: Leaving directory '/wrkdirs/usr/ports/graphics/librsvg2-rust/work/librsvg-2.50.3'
gmake[1]: *** [Makefile:825: all] Error 2
gmake[1]: Leaving directory '/wrkdirs/usr/ports/graphics/librsvg2-rust/work/librsvg-2.50.3'
===> Compilation failed unexpectedly.
Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the failure to
the maintainer.
*** Error code 1

Any hints what might be wrong? I'm especially perplexed by the seemingly
successful "done" status combined with the failed dependency. The complete
log is at
http://www.zefox.net/~fbsd/rpi4/librsvg2-rust-2.50.3_5.log 

Thanks for reading,

bob prohaska