Pass pack_t schemas into ukernels via auxinfo_t.

Details:
- Modified macro-kernels to pass the pack_t schema values for matrices
  A and B into the datatype-specific functions, where they are now
  inserted into a newly-expanded auxinfo_t struct. This gives gives the
  micro-kernels access to the pack_t schema values embedded in the
  control trees, which determine the precise format into which the
  matrix elements are packed.
- Updated a call to bli_packm_init_pack() in src/test_libblis.c to
  remove densify argument. Meant to include this in commit c472993b.

testsuite/src/test_libblis.c

@@ -1578,8 +1578,7 @@ void libblis_test_pobj_create( blksz_t* m, blksz_t* n, invdiag_t inv_diag, pack_
 	bli_obj_alias_to( *a, *p );
 
 	// Then initialize p appropriately for packing.
-	bli_packm_init_pack( FALSE,
-	                     inv_diag,
+	bli_packm_init_pack( inv_diag,
 	                     pack_schema,
 	                     BLIS_PACK_FWD_IF_UPPER,
 	                     BLIS_PACK_FWD_IF_LOWER,