Report error when using reference parameters in async methods
Report error when using reference parameters in async methods

Fixes bug 610624.

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