tests: add unit test for gst_caps_is_any() and _is_empty()
tests: add unit test for gst_caps_is_any() and _is_empty()

https://bugzilla.gnome.org//show_bug.cgi?id=731704

jpxiong/gstreamer,mparis/gstreamer,surround-io/gstreamer,mparis/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,mparis/gstreamer,krichter722/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,jpakkane/gstreamer,jpakkane/gstreamer,jpxiong/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,centricular/gstreamer,jpxiong/gstreamer,surround-io/gstreamer,krichter722/gstreamer,mparis/gstreamer,krichter722/gstreamer,surround-io/gstreamer,Lachann/gstreamer,centricular/gstreamer,Lachann/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,Lachann/gstreamer,krichter722/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,Lachann/gstreamer,shelsonjava/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer