mesa: enable OpenGL 3.1 with ARB_compatibility

Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Reviewed-by: Brian Paul <brianp@vmware.com>

docs/features.txt

@@ -24,10 +24,10 @@ not started
 
 # OpenGL Core and Compatibility context support
 
-OpenGL 3.1 and later versions are only supported with the Core profile.
-There are no plans to support GL_ARB_compatibility. The last supported OpenGL
-version with all deprecated features is 3.0. Some of the later GL features
-are exposed in the 3.0 context as extensions.
+Some drivers do not support the Compatibility profile or ARB_compatibility.
+Such drivers are limited to OpenGL 3.0 if the Core profile is not requested
+by applications. Some of the later GL features are exposed in the 3.0 context
+as extensions.
 
 
 Feature                                                 Status

docs/relnotes/18.1.0.html

@@ -26,8 +26,8 @@ Mesa 18.1.0 implements the OpenGL 4.5 API, but the version reported by
 glGetString(GL_VERSION) or glGetIntegerv(GL_MAJOR_VERSION) /
 glGetIntegerv(GL_MINOR_VERSION) depends on the particular driver being used.
 Some drivers don't support all the features required in OpenGL 4.5.  OpenGL
-4.5 is <strong>only</strong> available if requested at context creation
-because compatibility contexts are not supported.
+4.5 is <strong>only</strong> available if requested at context creation.
+Compatibility contexts may report a lower version depending on each driver.
 </p>
 
 
@@ -44,6 +44,7 @@ Note: some of the new features are only available with certain drivers.
 </p>
 
 <ul>
+<li>OpenGL 3.1 with ARB_compatibility on nv50, nvc0, r600, radeonsi, softpipe, llvmpipe, svga</li>
 <li>GL_ARB_bindless_texture on nvc0/maxwell+</li>
 <li>GL_EXT_semaphore on radeonsi</li>
 <li>GL_EXT_semaphore_fd on radeonsi</li>