st/mesa: remove outdated comment
st/mesa: remove outdated comment

The enable of AMD_performance_monitor is no longer related to whether
queries are run by the GPU since the commit mentioned below.

Suggested-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

commit ddf27a3dd062c78ff49a69a1396be4de9c1b5d37
Author: Nicolai Hähnle <nhaehnle@gmail.com>
Date:   Tue Nov 10 13:35:01 2015 +0100

    gallium: remove pipe_driver_query_group_info field type

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler