mesa: In conditional rendering fallback, check the query status.

mesa: In conditional rendering fallback, check the query status.

Otherwise, conditional rendering always takes the fallthrough "render it
anyway" case unless the application had itself done a check or wait on the
query.

Fixes intel oglconform's conditional_render advanced.nofbo.readpixels.

Reviewed-by: Brian Paul <brianp@vmware.com>
NOTE: This is a candidate for the 8.0 branch.