media-libs/libsfml: build and install pkgconfig on mingw-w64
This is an upstream commit, which will be in the 2.5.0 release, which
allows creation of the sfml pkgconfig files on mingw-w64 when either
SFML_INSTALL_PKGCONFIG_FILES is true or if their internal check
SFML_OS_SUPPORTS_PKGCONFIG returns true; since we explicitly set the
former this change will allow build and install of sfml pc files on
mingw-w64 and (I think) osx targets.
Closes: https://github.com/gentoo/gentoo/pull/7518
Package-Manager: Portage-2.3.24, Repoman-2.3.6