girparser: Add cprefix metadata argument for classes
girparser: Add cprefix metadata argument for classes

jessevdk/vala,Distrotech/vala,kamanashisroy/aroop,spidermonkdust/vala,kamanashisroy/aroop,rvu95/vala,flobrosch/vala-fixes,frida/vala,frida/vala,flobrosch/vala-fixes,GNOME/vala,rvu95/vala,Distrotech/vala,severinh/vala,GNOME/vala,severinh/vala,xdave/pvala,kamanashisroy/aroop,jessevdk/vala,rvu95/vala,playya/vala,Distrotech/vala,severinh/vala,playya/vala,playya/vala,GNOME/vala,tjol/vala-tjol,frida/vala,spidermonkdust/vala,frida/vala,spidermonkdust/vala,tjol/vala-tjol,GNOME/vala,flobrosch/vala-fixes,tjol/vala-tjol,frida/vala,jessevdk/vala