pkgconfig: Fix broken paths in -uninstalled.pc on Windows
pkgconfig: Fix broken paths in -uninstalled.pc on Windows

Fixes: #8668

mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,QuLogic/meson,QuLogic/meson,pexip/meson,mesonbuild/meson,QuLogic/meson,jpakkane/meson,jpakkane/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,QuLogic/meson,pexip/meson,pexip/meson,QuLogic/meson,mesonbuild/meson,jpakkane/meson,mesonbuild/meson,jpakkane/meson,jpakkane/meson,pexip/meson,pexip/meson,mesonbuild/meson,pexip/meson,jpakkane/meson,jpakkane/meson,pexip/meson,QuLogic/meson,jpakkane/meson,mesonbuild/meson,QuLogic/meson,QuLogic/meson,mesonbuild/meson,jpakkane/meson,QuLogic/meson