Refactor huge allocation to be managed by arenas.

Refactor huge allocation to be managed by arenas (though the global
red-black tree of huge allocations remains for lookup during
deallocation).  This is the logical conclusion of recent changes that 1)
made per arena dss precedence apply to huge allocation, and 2) made it
possible to replace the per arena chunk allocation/deallocation
functions.

Remove the top level huge stats, and replace them with per arena huge
stats.

Normalize function names and types to *dalloc* (some were *dealloc*).

Remove the --enable-mremap option.  As jemalloc currently operates, this
is a performace regression for some applications, but planned work to
logarithmically space huge size classes should provide similar amortized
performance.  The motivation for this change was that mremap-based huge
reallocation forced leaky abstractions that prevented refactoring.

include/jemalloc/internal/private_symbols.txt

@@ -5,6 +5,8 @@ arena_alloc_junk_small
 arena_bin_index
 arena_bin_info
 arena_boot
+arena_chunk_alloc_huge
+arena_chunk_dalloc_huge
 arena_dalloc
 arena_dalloc_bin
 arena_dalloc_bin_locked
@@ -86,7 +88,7 @@ base_alloc
 base_boot
 base_calloc
 base_node_alloc
-base_node_dealloc
+base_node_dalloc
 base_postfork_child
 base_postfork_parent
 base_prefork
@@ -103,13 +105,14 @@ bt_init
 buferror
 choose_arena
 choose_arena_hard
-chunk_alloc
+chunk_alloc_arena
+chunk_alloc_base
 chunk_alloc_default
 chunk_alloc_dss
 chunk_alloc_mmap
 chunk_boot
-chunk_dealloc
-chunk_dealloc_mmap
+chunk_dalloc_default
+chunk_dalloc_mmap
 chunk_dss_boot
 chunk_dss_postfork_child
 chunk_dss_postfork_parent
@@ -198,9 +201,7 @@ huge_allocated
 huge_boot
 huge_dalloc
 huge_dalloc_junk
-huge_dss_prec_get
 huge_malloc
-huge_mtx
 huge_ndalloc
 huge_nmalloc
 huge_palloc