Merge branch 'js/mingw-isatty' into maint

Update the isatty() emulation for Windows by updating the previous hack that depended on internals of (older) MSVC runtime. * js/mingw-isatty: mingw: replace isatty() hack mingw: fix colourization on Cygwin pseudo terminals mingw: adjust is_console() to work with stdin mingw: intercept isatty() to handle /dev/null as Git expects it