Upstream cygwin patches

[Leont]

Cygwin is currently applying these patches to their perl. I suspect we should apply them ourselves instead.

Note: I didn't write any of these, and can't vouch for them or test them.

[Leont]

The auto-image, hints, libsearch and readme patches look non-controversial to me.

The libpth patch had me confused for a moment. It's actually fixing a bug that exists on all platforms that use Configure, where include paths that don't end on /include will erroneously end up in libpth (e.g. /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include-fixed in my particular case). I would have written it differently but it seems correct (and necessary on other platforms as well).

The Win32 patch breaks on Windows, in particular Unicode.t. I think we should just leave it out.

[Tux]

Looks ok

[xenu]

The Win32 patch breaks on Windows, in particular Unicode.t. I think we should just leave it out.

Yeah, the Win32 part should be skipped. I don't understand the purpose of those changes and it seems leaving them out doesn't break the tests on cygwin.

[Leont]

I cut out the pieces that were controversial or seemed dubious, I think this can be merged in early 5.37

[tonycoz]

$ uname -a
CYGWIN_NT-10.0 GANYMEDE 3.3.5(0.341/5/3) 2022-05-13 12:27 x86_64 Cygwin