girparser: Handle unions inside boxed classes
girparser: Handle unions inside boxed classes

Fixes bug 649760.

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