Function gl::CopyTexImage2D

pub unsafe fn CopyTexImage2D(target: GLenum,
                             level: GLint,
                             internalformat: GLenum,
                             x: GLint,
                             y: GLint,
                             width: GLsizei,
                             height: GLsizei,
                             border: GLint)

Fallbacks: CopyTexImage2DEXT