Function gl::TexSubImage2D

pub unsafe fn TexSubImage2D(target: GLenum,
                            level: GLint,
                            xoffset: GLint,
                            yoffset: GLint,
                            width: GLsizei,
                            height: GLsizei,
                            format: GLenum,
                            type_: GLenum,
                            pixels: *const c_void)

Fallbacks: TexSubImage2DEXT