mesa: use GL_MAP_INVALIDATE_RANGE_BIT in glTexImage paths

mesa: use GL_MAP_INVALIDATE_RANGE_BIT in glTexImage paths

Update the dd.h docs to indicate that GL_MAP_INVALIDATE_RANGE_BIT
can be used with GL_MAP_WRITE_BIT when mapping renderbuffers and
texture images.

Pass the flag when mapping texture images for glTexImage, glTexSubImage,
etc.  It's up to drivers whether to actually make use of the flag.

NOTE: This is a candidate for the 8.0 branch.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>