Fixed a packing bug that manifested in trsm_r.

Details:
- Fixed a bug that caused a memory leak in the contiguous memory
  allocator. Because packm_init() was using simple aliasing when
  a subpartition object was marked as zeros by bli_acquire_mpart_*(),
  the "destination" pack object's mem_t entry was being overwritten
  by the corresponding field of the "source" object (which was likely
  NULL). This prevented the block from being released back to the
  memory allocator. But this bug only manifested when changing the
  location of packing B from outside the var1 loop to inside the
  var3 loop, and only for trsm with triangular B (side = right). The
  bug was fixed by changing the type of alias used in packm_init()
  when handling zero partition cases. Specifically, we now use
  bli_obj_alias_for_packing(), which does not clobber the destination
  (pack) object's mem_t field. Thanks to Devangi Parikh for this bug
  report.

frame/1m/packm/bli_packm_init.c

@@ -95,10 +95,15 @@ void bli_packm_init( obj_t*   a,
 	}
 
 	// If the object is marked as being filled with zeros, then we can skip
-	// the packm operation entirely and alias.
+	// the packm operation entirely and alias. Notice that we use pack-aware
+	// aliasing. This is needed because the object may have been packed in
+	// a previous iteration, which means the object currently contains the
+	// mem_t entry of an already-allocated block. bli_obj_alias_for_packing()
+	// will avoid overwriting that mem_t entry, which means it can be
+	// properly released later on.
 	if ( bli_obj_is_zeros( *a ) )
 	{
-		bli_obj_alias_to( *a, *p );
+		bli_obj_alias_for_packing( *a, *p );
 		return;
 	}