mesa: detect inefficient buffer use and report through debug output

mesa: detect inefficient buffer use and report through debug output

When a buffer is created with GL_STATIC_DRAW, its contents should not
be changed frequently.  But that's exactly what one application I'm
debugging does.  This patch adds code to try to detect inefficient
buffer use in a couple places.  The GL_ARB_debug_output mechanism is
used to report the issue.

NVIDIA's driver detects these sort of things too.

Other types of inefficient buffer use could also be detected in the
future.

Reviewed-by: José Fonseca <jfonseca@vmware.com>