i965: Fix allow_higher_compat_version workaround limited by OpenGL 3.0

Added check for higher compat profile being allowed
before assigning certain extensions.

Fixes: 272fe949 (mesa: enable ARB_texture_buffer_* extensions in the Compatibility profile)

Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Signed-off-by: Yevhenii Kolesnikov <yevhenii.kolesnikov@globallogic.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107052
(cherry picked from commit 07f4b4e4)