st/mesa: add EXT_polygon_offset_clamp support

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Glenn Kennard <glenn.kennard@gmail.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
diff --git a/docs/relnotes/10.5.0.html b/docs/relnotes/10.5.0.html
index bf932d4..578db4f 100644
--- a/docs/relnotes/10.5.0.html
+++ b/docs/relnotes/10.5.0.html
@@ -47,7 +47,7 @@
 <li>GL_ARB_framebuffer_sRGB on freedreno</li>
 <li>GL_ARB_texture_rg on freedreno</li>
 <li>GL_EXT_packed_float on freedreno</li>
-<li>GL_EXT_polygon_offset_clamp on i965</li>
+<li>GL_EXT_polygon_offset_clamp on i965, nv50, nvc0, r600, radeonsi, llvmpipe</li>
 <li>GL_EXT_texture_shared_exponent on freedreno</li>
 <li>GL_EXT_texture_snorm on freedreno</li>
 </ul>