Details:
- Added support for an experimental gemm macro-kernel incrementally
packs one micro-panel of B at a time. This is useful for certain
special cases of gemm where m is small.
- Minor changes to default values of clarksville configuration.
- Defined BLIS_PACKED_BLOCKS as part of pack_t type, even though we
do not yet have any use (or implementation support) for block storage.
- Comment update to bli_packm_init.c.