Fix potential chunk leaks.

Move chunk_dalloc_arena()'s implementation into chunk_dalloc_wrapper(),
so that if the dalloc hook fails, proper decommit/purge/retain cascading
occurs.  This fixes three potential chunk leaks on OOM paths, one during
dss-based chunk allocation, one during chunk header commit (currently
relevant only on Windows), and one during rtree write (e.g. if rtree
node allocation fails).

Merge chunk_purge_arena() into chunk_purge_default() (refactor, no
change to functionality).

include/jemalloc/internal/chunk.h

@@ -62,12 +62,8 @@ void	*chunk_alloc_wrapper(arena_t *arena, chunk_hooks_t *chunk_hooks,
     void *new_addr, size_t size, size_t alignment, bool *zero, bool *commit);
 void	chunk_dalloc_cache(arena_t *arena, chunk_hooks_t *chunk_hooks,
     void *chunk, size_t size, bool committed);
-void	chunk_dalloc_arena(arena_t *arena, chunk_hooks_t *chunk_hooks,
-    void *chunk, size_t size, bool zeroed, bool committed);
 void	chunk_dalloc_wrapper(arena_t *arena, chunk_hooks_t *chunk_hooks,
-    void *chunk, size_t size, bool committed);
-bool	chunk_purge_arena(arena_t *arena, void *chunk, size_t offset,
-    size_t length);
+    void *chunk, size_t size, bool zeroed, bool committed);
 bool	chunk_purge_wrapper(arena_t *arena, chunk_hooks_t *chunk_hooks,
     void *chunk, size_t size, size_t offset, size_t length);
 bool	chunk_boot(void);

include/jemalloc/internal/private_symbols.txt

@@ -152,7 +152,6 @@ chunk_alloc_dss
 chunk_alloc_mmap
 chunk_alloc_wrapper
 chunk_boot
-chunk_dalloc_arena
 chunk_dalloc_cache
 chunk_dalloc_mmap
 chunk_dalloc_wrapper
@@ -172,7 +171,6 @@ chunk_npages
 chunk_postfork_child
 chunk_postfork_parent
 chunk_prefork
-chunk_purge_arena
 chunk_purge_wrapper
 chunk_register
 chunks_rtree