Normalize size classes.

Normalize size classes to use the same number of size classes per size
doubling (currently hard coded to 4), across the intire range of size
classes.  Small size classes already used this spacing, but in order to
support this change, additional small size classes now fill [4 KiB .. 16
KiB).  Large size classes range from [16 KiB .. 4 MiB).  Huge size
classes now support non-multiples of the chunk size in order to fill (4
MiB .. 16 MiB).

include/jemalloc/internal/chunk.h

@@ -40,9 +40,6 @@ extern rtree_t		*chunks_rtree;
 extern size_t		chunksize;
 extern size_t		chunksize_mask; /* (chunksize - 1). */
 extern size_t		chunk_npages;
-extern size_t		map_bias; /* Number of arena chunk header pages. */
-extern size_t		map_misc_offset;
-extern size_t		arena_maxclass; /* Max size class for arenas. */
 
 void	*chunk_alloc_base(size_t size);
 void	*chunk_alloc_arena(chunk_alloc_t *chunk_alloc,