gvariant module: Fix memory leak when deserializing hashtables with gvariant
gvariant module: Fix memory leak when deserializing hashtables with gvariant

Fixes bug 698260

GNOME/vala,flobrosch/vala-fixes,frida/vala,frida/vala,frida/vala,GNOME/vala,GNOME/vala,frida/vala,spidermonkdust/vala,flobrosch/vala-fixes,spidermonkdust/vala,frida/vala,spidermonkdust/vala,rvu95/vala,flobrosch/vala-fixes,rvu95/vala,rvu95/vala,GNOME/vala