parse: add prototypes for unused functions to avoid compiler warning
parse: add prototypes for unused functions to avoid compiler warning

The warning is never fatal, because we don't use -Werror for the
parser helper library build, but the warnings are annoying anyway.

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