-extern void
-_mesa_Viewport( GLint x, GLint y, GLsizei width, GLsizei height );
-
-extern void
-_mesa_set_viewport( GLcontext *ctx, GLint x, GLint y, GLsizei width, GLsizei height );
-
-extern void
-_mesa_DepthRange( GLclampd nearval, GLclampd farval );
-