Made Vulkan default renderer backend on Linux.
Made Vulkan default renderer backend on Linux.

bkaradzic/bgfx,emoon/bgfx,LWJGL-CI/bgfx,bkaradzic/bgfx,bkaradzic/bgfx,jdryg/bgfx,jdryg/bgfx,LWJGL-CI/bgfx,LWJGL-CI/bgfx,jdryg/bgfx,jdryg/bgfx,emoon/bgfx,bkaradzic/bgfx,LWJGL-CI/bgfx,emoon/bgfx