Move centralized chunk management into arenas.

Migrate all centralized data structures related to huge allocations and
recyclable chunks into arena_t, so that each arena can manage huge
allocations and recyclable virtual memory completely independently of
other arenas.

Add chunk node caching to arenas, in order to avoid contention on the
base allocator.

Use chunks_rtree to look up huge allocations rather than a red-black
tree.  Maintain a per arena unsorted list of huge allocations (which
will be needed to enumerate huge allocations during arena reset).

Remove the --enable-ivsalloc option, make ivsalloc() always available,
and use it for size queries if --enable-debug is enabled.  The only
practical implications to this removal are that 1) ivsalloc() is now
always available during live debugging (and the underlying radix tree is
available during core-based debugging), and 2) size query validation can
no longer be enabled independent of --enable-debug.

Remove the stats.chunks.{current,total,high} mallctls, and replace their
underlying statistics with simpler atomically updated counters used
exclusively for gdump triggering.  These statistics are no longer very
useful because each arena manages chunks independently, and per arena
statistics provide similar information.

Simplify chunk synchronization code, now that base chunk allocation
cannot cause recursive lock acquisition.

include/jemalloc/internal/private_symbols.txt

@@ -60,6 +60,8 @@ arena_miscelm_to_pageind
 arena_miscelm_to_rpages
 arena_nbound
 arena_new
+arena_node_alloc
+arena_node_dalloc
 arena_palloc
 arena_postfork_child
 arena_postfork_parent
@@ -103,8 +105,6 @@ atomic_sub_z
 base_alloc
 base_allocated_get
 base_boot
-base_node_alloc
-base_node_dalloc
 base_postfork_child
 base_postfork_parent
 base_prefork
@@ -130,6 +130,7 @@ chunk_alloc_mmap
 chunk_boot
 chunk_dalloc_default
 chunk_dalloc_mmap
+chunk_deregister
 chunk_dss_boot
 chunk_dss_postfork_child
 chunk_dss_postfork_parent
@@ -137,12 +138,13 @@ chunk_dss_prec_get
 chunk_dss_prec_set
 chunk_dss_prefork
 chunk_in_dss
+chunk_lookup
 chunk_npages
 chunk_postfork_child
 chunk_postfork_parent
 chunk_prefork
+chunk_register
 chunk_unmap
-chunks_mtx
 chunks_rtree
 chunksize
 chunksize_mask
@@ -218,16 +220,12 @@ hash_x86_128
 hash_x86_32
 huge_aalloc
 huge_allocated
-huge_boot
 huge_dalloc
 huge_dalloc_junk
 huge_malloc
 huge_ndalloc
 huge_nmalloc
 huge_palloc
-huge_postfork_child
-huge_postfork_parent
-huge_prefork
 huge_prof_tctx_get
 huge_prof_tctx_set
 huge_ralloc