mesa: Add bufferobj_range_mapped function

mesa: Add bufferobj_range_mapped function

Add function to test if the buffer is already mapped and if so,
if the mapped range overlaps the given range.
Modify the _mesa_InvalidateBufferSubData function to use
the new function.

Enable buffer_object_subdata_range_good() to use bufferobj_range_mapped

Reviewed-by: Brian Paul <brianp@vmware.com>