Add gstcaps2.h for installation so gst-plugins builds.
Add gstcaps2.h for installation so gst-plugins builds.

Original commit message from CVS:
Add gstcaps2.h for installation so gst-plugins builds.

surround-io/gstreamer,Distrotech/gstreamer,drothlis/gstreamer,magcius/gstreamer,shelsonjava/gstreamer,Lachann/gstreamer,ahmedammar/platform_external_gst_gstreamer,ylatuya/gstreamer,shelsonjava/gstreamer,lubosz/gstreamer,collects/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,collects/gstreamer,lovebug356/gstreamer,ylatuya/gstreamer,lubosz/gstreamer,ensonic/gstreamer,krichter722/gstreamer,collects/gstreamer,cablelabs/gstreamer,cablelabs/gstreamer,krichter722/gstreamer,jpakkane/gstreamer,krieger-od/gstreamer,StreamUtils/gstreamer,lovebug356/gstreamer,jpakkane/gstreamer,ensonic/gstreamer,mrchapp/gstreamer,krieger-od/gstreamer,mparis/gstreamer,cfoch/gstreamer,centricular/gstreamer,ahmedammar/platform_external_gst_gstreamer,magcius/gstreamer,ensonic/gstreamer,Lachann/gstreamer,ahmedammar/platform_external_gst_gstreamer,drothlis/gstreamer,collects/gstreamer,surround-io/gstreamer,jpxiong/gstreamer,cfoch/gstreamer,drothlis/gstreamer,jpakkane/gstreamer,cfoch/gstreamer,mrchapp/gstreamer,jpxiong/gstreamer,surround-io/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,StreamUtils/gstreamer,drothlis/gstreamer,cfoch/gstreamer,ylatuya/gstreamer,cablelabs/gstreamer,krieger-od/gstreamer,ylatuya/gstreamer,jpakkane/gstreamer,ensonic/gstreamer,Distrotech/gstreamer,collects/gstreamer,jpakkane/gstreamer,lovebug356/gstreamer,lubosz/gstreamer,mparis/gstreamer,ensonic/gstreamer,surround-io/gstreamer,krichter722/gstreamer,Distrotech/gstreamer,justinjoy/gstreamer,lubosz/gstreamer,StreamUtils/gstreamer,cablelabs/gstreamer,lovebug356/gstreamer,lubosz/gstreamer,StreamUtils/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,centricular/gstreamer,krieger-od/gstreamer,StreamUtils/gstreamer,krieger-od/gstreamer,mrchapp/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,krichter722/gstreamer,centricular/gstreamer,Distrotech/gstreamer,mrchapp/gstreamer,centricular/gstreamer,ahmedammar/platform_external_gst_gstreamer,centricular/gstreamer,magcius/gstreamer,magcius/gstreamer,justinjoy/gstreamer,Lachann/gstreamer,ylatuya/gstreamer,Distrotech/gstreamer,mparis/gstreamer,jpxiong/gstreamer,jpxiong/gstreamer,cfoch/gstreamer,justinjoy/gstreamer,lovebug356/gstreamer,Lachann/gstreamer,justinjoy/gstreamer,Lachann/gstreamer,ahmedammar/platform_external_gst_gstreamer,justinjoy/gstreamer,magcius/gstreamer,mrchapp/gstreamer,drothlis/gstreamer