Merge branch 'js/msys2'

Beginning of the upstreaming process of Git for Windows effort. * js/msys2: mingw: uglify (a, 0) definitions to shut up warnings mingw: squash another warning about a cast mingw: avoid warnings when casting HANDLEs to int mingw: avoid redefining S_* constants compat/winansi: support compiling with MSys2 compat/mingw: support MSys2-based MinGW build nedmalloc: allow compiling with MSys2's compiler config.mak.uname: supporting 64-bit MSys2 config.mak.uname: support MSys2