pkgconfig: in -uninstalled ensure to link with the proper library
pkgconfig: in -uninstalled ensure to link with the proper library

Fixes build of GStreamer in gst-uninstalled on OSX with older liborc
installed from macports at '/opt/local'.

ijsf/OpenWebRTC-orc,MOXfiles/orc,ijsf/OpenWebRTC-orc,Distrotech/orc,jpakkane/orc,Distrotech/orc,mojaves/orc,mojaves/orc,jpakkane/orc,mojaves/orc,MOXfiles/orc,ijsf/OpenWebRTC-orc,jpakkane/orc,Distrotech/orc,MOXfiles/orc