SCons: Disable -Werror on 'stable' releases
SCons: Disable -Werror on 'stable' releases

Stable releases are tagged and need to stay easy to compile in the future.
As new compiler versions introduce new warnings or catch more occurrences,
have -Werror set in tagged releases could be a bother.

We still want it on by default for all Godot developers, so it's now
conditional.

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