mesa: Also initialize gl_performance_monitor::Active.

The i965 implementation uses calloc, so I missed this.  It's best to
simply initialize it to avoid requiring a zeroing allocator, though.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/mesa/main/performance_monitor.c

@@ -64,6 +64,8 @@ new_performance_monitor(struct gl_context *ctx, GLuint index)
 
    m->Name = index;
 
+   m->Active = false;
+
    m->ActiveGroups =
       rzalloc_array(NULL, unsigned, ctx->PerfMonitor.NumGroups);