codegen: Fix crash when concatenating array parameters
codegen: Fix crash when concatenating array parameters

Fixes bug 570846.

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