girparser: Support async constructors.
girparser: Support async constructors.

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