maintainer-feedback requested: [Bug 268514] graphics/png: missing symbol after upgrading from 1.6.37 to 1.6.38

Bugzilla Automation <bugzilla@FreeBSD.org> has asked freebsd-desktop (Team)
<desktop@FreeBSD.org> for maintainer-feedback:
Bug 268514: graphics/png: missing symbol after upgrading from 1.6.37 to 1.6.38
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=268514



--- Description ---
After upgrading to libpng 1.6.38 through the ports framework all ports using
libpng are broken. The error is:

  /usr/local/lib/libpng16.so.16: version PNG16_0 required by /usr/local/bin/xv
not defined

Downgrading to 1.6.37 restores a working state. It seems this error is due to
the switch to cmake as build system. Using autoconf to build 1.6.38 results in
a package that can be used to upgrade the installed version and ports using
libpng keep working, eg. xv.

Looking at the symbol table of libpng16.so shows that all exported png_ symbols
lack the @@PNG16_0 suffix that is used with an autoconf build. The update to
1.6.39 does not fix this issue.