PkgConfigDependency: Search for pkg-config with ExternalProgram
PkgConfigDependency: Search for pkg-config with ExternalProgram

Strawberry Perl on Windows ships with a Perl implementation of
pkg-config embedded inside a BAT file. True horror of horrors, but
people do use it, so search for pkg-config with ExternalProgram which
has the right Windows-specific cases to deal with that.

Closes https://github.com/mesonbuild/meson/issues/3221

mesonbuild/meson,thiblahute/meson,jpakkane/meson,jpakkane/meson,thiblahute/meson,QuLogic/meson,jeandet/meson,MathieuDuponchelle/meson,pexip/meson,pexip/meson,becm/meson,pexip/meson,thiblahute/meson,MathieuDuponchelle/meson,becm/meson,pexip/meson,MathieuDuponchelle/meson,jpakkane/meson,thiblahute/meson,becm/meson,mesonbuild/meson,mesonbuild/meson,MathieuDuponchelle/meson,pexip/meson,mesonbuild/meson,QuLogic/meson,jpakkane/meson,QuLogic/meson,jeandet/meson,pexip/meson,mesonbuild/meson,MathieuDuponchelle/meson,becm/meson,becm/meson,MathieuDuponchelle/meson,QuLogic/meson,MathieuDuponchelle/meson,mesonbuild/meson,becm/meson,becm/meson,MathieuDuponchelle/meson,pexip/meson,thiblahute/meson,mesonbuild/meson,jpakkane/meson,pexip/meson,jeandet/meson,becm/meson,mesonbuild/meson,becm/meson,jpakkane/meson,jeandet/meson,jpakkane/meson,MathieuDuponchelle/meson,QuLogic/meson,becm/meson,jpakkane/meson,jeandet/meson,QuLogic/meson,thiblahute/meson,jeandet/meson,QuLogic/meson,jeandet/meson,thiblahute/meson,pexip/meson,jpakkane/meson,QuLogic/meson,thiblahute/meson,jeandet/meson,jeandet/meson,mesonbuild/meson,pexip/meson,thiblahute/meson,mesonbuild/meson,QuLogic/meson