conf-zlib: update for ortools_solvers

[tbrk]

Changes allowing conf-zlib to be used as a dependency for ortools_solvers.

for centos < 10: include zlib-static
for centos >= 10: use zlib-ng-compat-devel
add msys2
add suse and opensuse
add freebsd

[jmid]

Thanks! Improvements to conf-zlib are most welcome! 🙏

I can see conf-zlib.1/opam has been improved over the past 10 years.
Rather than roll a version 2 (which opens up for, e.g., unwanted lower-bound conf-zlib search) I propose adding these changes to the original file.

The MSys2 changes are not quite right.

We offer 2 options to build standalone Windows executables:

• MinGW distributed through Cygwin
• MinGW distributed through MSys2

This however requires installing the packages prefixed with mingw,
as the regular Cygwin/MSys2 packages will introduce a dependency on their runtimes (cygwin1.dll and similar for MSys2). This means using

• https://packages.msys2.org/packages/mingw-w64-x86_64-zlib for 64-bit MSys2-MinGW
• https://packages.msys2.org/packages/mingw-w64-i686-zlib for 32-bit Msys2-MinGW
• as an alternative there's also https://packages.msys2.org/packages/mingw-w64-x86_64-zlib-ng-compat but only for or 64-bit MSys2-MinGW
• https://cygwin.com/packages/summary/mingw64-x86_64-zlib.html for 64-bit Cygwin-MinGW
• https://cygwin.com/packages/summary/mingw64-i686-zlib.html for 32-bit Cygwin-MinGW

For more background on MinGW conf-packaging see

• the template PR #26072
• the fix PR correcting a subtle side condition typo #28939

[jmid]

Looking some more, MinGW support for zlib was already added in e776c77 and had its side-condition fixed in 0b29baf. With that in mind, I don't understand what these MSys2 changes are supposed to fix... 🤔