pgSphere compilation under mingw64/msys2 for windows

[Regina Obe]

Gandalf,

Just a followup to this discussion we had in November -
https://lists.osgeo.org/pipermail/postgis-users/2023-November/046247.html

Wasn't sure if you had any luck compiling pgSphere.   I looked at it again
and was able to.

I reported the issue I had, and they are planning to make some revisions to
it compiles cleanly for mingw64/msys2

https://github.com/postgrespro/pgsphere/issues/122

Not sure if it is similar issues with Visual Studio.

I still haven't tried compiling with USE_HEALPIX=1 though.

But anyway when they release the new version with the patch, I plan to make
binaries available and if all goes well eventually include in the PostGIS
Windows Bundle (might need to change the name to Spatial Bundle, since this
doesn't rely/work with PostGIS) like the other extensions I include.

Thanks,
Regina