Always initialize VariantCall return_type.
Always initialize VariantCall return_type.

The return_type is used by the GDScript parser (and possibly other
scripting languages), so it MUST be initialized at least.
It could be initialized to Variant::NIL in release, but I see no reason
for not setting the actual value.
See similar issue in 95dfa5b .

vkbsb/godot,groud/godot,sanikoyes/godot,vkbsb/godot,sanikoyes/godot,Faless/godot,ZuBsPaCe/godot,Paulloz/godot,Faless/godot,MarianoGnu/godot,Paulloz/godot,josempans/godot,godotengine/godot,ex/godot,vnen/godot,vkbsb/godot,pkowal1982/godot,godotengine/godot,firefly2442/godot,BastiaanOlij/godot,josempans/godot,honix/godot,okamstudio/godot,akien-mga/godot,pkowal1982/godot,ex/godot,okamstudio/godot,Faless/godot,Paulloz/godot,akien-mga/godot,Zylann/godot,ZuBsPaCe/godot,Faless/godot,pkowal1982/godot,Shockblast/godot,josempans/godot,firefly2442/godot,Shockblast/godot,okamstudio/godot,MarianoGnu/godot,MarianoGnu/godot,guilhermefelipecgs/godot,akien-mga/godot,pkowal1982/godot,vnen/godot,Paulloz/godot,okamstudio/godot,MarianoGnu/godot,godotengine/godot,Valentactive/godot,firefly2442/godot,DmitriySalnikov/godot,ex/godot,josempans/godot,guilhermefelipecgs/godot,Shockblast/godot,MarianoGnu/godot,firefly2442/godot,BastiaanOlij/godot,Faless/godot,Valentactive/godot,okamstudio/godot,Paulloz/godot,akien-mga/godot,Shockblast/godot,ZuBsPaCe/godot,Zylann/godot,BastiaanOlij/godot,josempans/godot,honix/godot,DmitriySalnikov/godot,MarianoGnu/godot,ex/godot,guilhermefelipecgs/godot,BastiaanOlij/godot,groud/godot,godotengine/godot,Shockblast/godot,Zylann/godot,ex/godot,guilhermefelipecgs/godot,honix/godot,Faless/godot,Shockblast/godot,ex/godot,guilhermefelipecgs/godot,Shockblast/godot,DmitriySalnikov/godot,BastiaanOlij/godot,vkbsb/godot,Zylann/godot,DmitriySalnikov/godot,akien-mga/godot,ZuBsPaCe/godot,Paulloz/godot,Valentactive/godot,honix/godot,groud/godot,ex/godot,pkowal1982/godot,Valentactive/godot,guilhermefelipecgs/godot,firefly2442/godot,Paulloz/godot,vnen/godot,Valentactive/godot,ex/godot,Shockblast/godot,okamstudio/godot,ZuBsPaCe/godot,MarianoGnu/godot,josempans/godot,ZuBsPaCe/godot,honix/godot,akien-mga/godot,okamstudio/godot,vnen/godot,groud/godot,sanikoyes/godot,groud/godot,Zylann/godot,Faless/godot,groud/godot,akien-mga/godot,vkbsb/godot,MarianoGnu/godot,godotengine/godot,guilhermefelipecgs/godot,okamstudio/godot,Zylann/godot,sanikoyes/godot,godotengine/godot,firefly2442/godot,josempans/godot,godotengine/godot,pkowal1982/godot,okamstudio/godot,honix/godot,Zylann/godot,godotengine/godot,BastiaanOlij/godot,Valentactive/godot,Valentactive/godot,pkowal1982/godot,Valentactive/godot,firefly2442/godot,vnen/godot,sanikoyes/godot,firefly2442/godot,sanikoyes/godot,akien-mga/godot,BastiaanOlij/godot,guilhermefelipecgs/godot,DmitriySalnikov/godot,vkbsb/godot,vnen/godot,vnen/godot,vnen/godot,Zylann/godot,vkbsb/godot,BastiaanOlij/godot,sanikoyes/godot,Faless/godot,vkbsb/godot,sanikoyes/godot,josempans/godot,okamstudio/godot,ZuBsPaCe/godot,DmitriySalnikov/godot,ZuBsPaCe/godot,pkowal1982/godot,DmitriySalnikov/godot