Added check to prevent multiple calls to bgfx init.
Added check to prevent multiple calls to bgfx init.

sergeScherbakov/bgfx,aonorin/bgfx,0-wiz-0/bgfx,BlueCrystalLabs/bgfx,emoon/bgfx,mmicko/bgfx,MikePopoloski/bgfx,mcanthony/bgfx,mmicko/bgfx,ocornut/bgfx,BlueCrystalLabs/bgfx,aonorin/bgfx,fluffyfreak/bgfx,ktotheoz/bgfx,LWJGL-CI/bgfx,Vertexwahn/bgfx,ocornut/bgfx,mendsley/bgfx,ocornut/bgfx,cuavas/bgfx,cuavas/bgfx,cyndis/bgfx,v3n/bgfx,jdryg/bgfx,jpcy/bgfx,mendsley/bgfx,andr3wmac/bgfx,ktotheoz/bgfx,septag/bgfx,elmindreda/bgfx,bkaradzic/bgfx,cuavas/bgfx,ming4883/bgfx,emoon/bgfx,fluffyfreak/bgfx,ktotheoz/bgfx,LWJGL-CI/bgfx,darkimage/bgfx,Extrawurst/bgfx,fluffyfreak/bgfx,LSBOSS/bgfx,janstk/bgfx,Synxis/bgfx,septag/bgfx,Vertexwahn/bgfx,LSBOSS/bgfx,jdryg/bgfx,jpcy/bgfx,kondrak/bgfx,cyndis/bgfx,LWJGL-CI/bgfx,elmindreda/bgfx,ming4883/bgfx,MikePopoloski/bgfx,janstk/bgfx,ming4883/bgfx,mcanthony/bgfx,marco-we/bgfx,mmicko/bgfx,Vertexwahn/bgfx,mendsley/bgfx,darkimage/bgfx,bkaradzic/bgfx,septag/bgfx,BlueCrystalLabs/bgfx,kondrak/bgfx,attilaz/bgfx,janstk/bgfx,LWJGL-CI/bgfx,bkaradzic/bgfx,aonorin/bgfx,cyndis/bgfx,andr3wmac/bgfx,v3n/bgfx,kondrak/bgfx,attilaz/bgfx,LSBOSS/bgfx,sergeScherbakov/bgfx,mcanthony/bgfx,sergeScherbakov/bgfx,jpcy/bgfx,jdryg/bgfx,jdryg/bgfx,Synxis/bgfx,Synxis/bgfx,jpcy/bgfx,emoon/bgfx,darkimage/bgfx,fluffyfreak/bgfx,marco-we/bgfx,MikePopoloski/bgfx,Extrawurst/bgfx,marco-we/bgfx,bkaradzic/bgfx,andr3wmac/bgfx,elmindreda/bgfx,attilaz/bgfx,0-wiz-0/bgfx,Extrawurst/bgfx,0-wiz-0/bgfx,v3n/bgfx