I installed these two libraries, autoconf'ed myself a new configure
script, and rebuilt XEmacs 21.2, without any problems. Not that I've
stress-tested them or anything.
I've updated the tarballs for these packages at:
ftp://ftp.xemacs.org/pub/xemacs/aux
Hopefully there are bug fixes in libpng 1.0.3 that lays to rest the
complaints about various bugs libpng 1.0.2. (our configure script
only accepts 1.0.2 and later).
Martin