GL: Check if extension exist before setting border color.
GL: Check if extension exist before setting border color.

elmindreda/bgfx,mcanthony/bgfx,Synxis/bgfx,aonorin/bgfx,LWJGL-CI/bgfx,attilaz/bgfx,mmicko/bgfx,jdryg/bgfx,mendsley/bgfx,bkaradzic/bgfx,emoon/bgfx,darkimage/bgfx,Synxis/bgfx,marco-we/bgfx,MikePopoloski/bgfx,jdryg/bgfx,0-wiz-0/bgfx,0-wiz-0/bgfx,fluffyfreak/bgfx,attilaz/bgfx,LSBOSS/bgfx,andr3wmac/bgfx,marco-we/bgfx,kondrak/bgfx,LSBOSS/bgfx,Synxis/bgfx,BlueCrystalLabs/bgfx,kondrak/bgfx,mendsley/bgfx,fluffyfreak/bgfx,LSBOSS/bgfx,MikePopoloski/bgfx,jpcy/bgfx,mmicko/bgfx,septag/bgfx,jpcy/bgfx,jdryg/bgfx,mcanthony/bgfx,BlueCrystalLabs/bgfx,kondrak/bgfx,bkaradzic/bgfx,andr3wmac/bgfx,fluffyfreak/bgfx,mendsley/bgfx,mmicko/bgfx,BlueCrystalLabs/bgfx,v3n/bgfx,septag/bgfx,darkimage/bgfx,cuavas/bgfx,bkaradzic/bgfx,fluffyfreak/bgfx,emoon/bgfx,jpcy/bgfx,jdryg/bgfx,LWJGL-CI/bgfx,v3n/bgfx,jpcy/bgfx,septag/bgfx,mcanthony/bgfx,attilaz/bgfx,LWJGL-CI/bgfx,aonorin/bgfx,elmindreda/bgfx,darkimage/bgfx,andr3wmac/bgfx,v3n/bgfx,cuavas/bgfx,elmindreda/bgfx,bkaradzic/bgfx,aonorin/bgfx,0-wiz-0/bgfx,emoon/bgfx,LWJGL-CI/bgfx,cuavas/bgfx,MikePopoloski/bgfx,marco-we/bgfx