More memory alignment-related tweaks.

Details:
- Renamed BLIS_MEMORY_ALIGNMENT_SIZE to BLIS_CONTIG_MEM_ALIGN_SIZE.
- Renamed BLIS_ENABLE_MEMORY_ALIGNMENT to BLIS_ENABLE_SYSTEM_MEM_ALIGN.
- Added BLIS_SYSTEM_MEM_ALIGN_SIZE, which controls only the alignment
  passed into posix_memalign() or equivalent.
- Defined new function, bli_align_dim_to_cmem(), which applies the
  contiguous memory alignment (rather than the system/malloc alignment).

frame/base/bli_malloc.c

@@ -41,9 +41,9 @@ void* bli_malloc( siz_t size )
 
 	if ( size == 0 ) return NULL;
 
-#ifdef BLIS_ENABLE_MEMORY_ALIGNMENT
+#ifdef BLIS_ENABLE_SYSTEM_MEM_ALIGN
 	r_val = posix_memalign( &p,
-	                        ( size_t ) BLIS_MEMORY_ALIGNMENT_SIZE,
+	                        ( size_t ) BLIS_SYSTEM_MEM_ALIGN_SIZE,
 	                        ( size_t ) size );
 
 	if ( r_val != 0 ) bli_abort();