main: Add entry point for NamedBufferSubData.

v2: review by Ian Romanick
   - Remove "_mesa" from name of static software fallback buffer_sub_data.
   - Remove mappedRange from _mesa_buffer_sub_data.
   - Removed some cosmetic changes to a separate commit.

Reviewed-by: Martin Peres <martin.peres@linux.intel.com>
4 files changed