[libpng] No hardware optimisation enabled for PowerPC architecture about vcpkg

[dg0yt]

For example in Fedora Linux, the RPM spec file does not do anything special with configure and make part (ref https://src.fedoraproject.org/rpms/libpng/blob/rawhide/f/libpng.spec#_71) so the logic of upstream CMakeList must be correct.

No. Fedora (and the "additional context" in your initial post) use autotools/configure/make. This is independent of CMake. And that might explain why nobody on linux noticed the problem.

[dg0yt]

Might be an upstream issue, cf. #38250 (comment)

[runlevel5]

@dg0yt it is plausible though I do not think it is an issue upstream. For example in Fedora Linux, the RPM spec file does not do anything special with configure and make part (ref https://src.fedoraproject.org/rpms/libpng/blob/rawhide/f/libpng.spec#_71) so the logic of upstream CMakeList must be correct. One way to verify that is that I use the /usr/lib64/libpng16.a (belongs to libpng-static package on Fedora 40 ppc64le) and the app does not complain anymore.