Added `textureCube` macro for GLSL  >= 130. (#2728)
Added `textureCube` macro for GLSL  >= 130. (#2728)

`textureCube` requires extension `GL_NV_shadow_samplers_cube`, however `texture` can sample a cube sampler without the extension.
LWJGL-CI/bgfx,bkaradzic/bgfx,bkaradzic/bgfx,bkaradzic/bgfx,LWJGL-CI/bgfx,LWJGL-CI/bgfx,LWJGL-CI/bgfx,bkaradzic/bgfx