nanovg: Allow texture update after creation.
nanovg: Allow texture update after creation.

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