mesa: fix UBO queries for active uniforms

mesa: fix UBO queries for active uniforms

Commit 34df5eb introduced regression to GetActiveUniformBlockiv
when querying one of the following properties:

   GL_UNIFORM_BLOCK_ACTIVE_UNIFORMS
   GL_UNIFORM_BLOCK_ACTIVE_UNIFORM_INDICES

Implementation counted all uniforms in ubo directly while query should
check first if the uniform in question is _active_.

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90109
Reviewed-By: Martin Peres <martin.peres@linux.intel.com>