mesa: Add core support for the GL_INTEL_performance_query extension.

mesa: Add core support for the GL_INTEL_performance_query extension.

Like AMD_performance_monitor, this extension provides an interface for
applications (and OpenGL-based tools) to access GPU performance
counters. Since the exact performance counters available vary between
vendors and hardware generations, the extension provides an API the
application can use to get the names, types, and minimum/maximum
values of all available counters.

Applications create performance queries based on available query
types, and begin/end measurement collection. Multiple queries can be
measuring simultaneously.

v2: Whitespace changes
v3: src/mapi/glapi/gen/gl_API.xml: Also expose the functions to GLES2.
v4: Whitespace changes, static_dispatch="false" for all functions, fix
    dispatch_sanity test for GLES2 functions

Signed-off-by: Petri Latvala <petri.latvala@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>