Travis: Disable -Wstrict-aliasing warning on GCC 5 test build
Travis: Disable -Wstrict-aliasing warning on GCC 5 test build

Should speed up builds by avoiding warning spam.
This warning is no longer raised by newer GCC versions.

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