Attempt mmap-based in-place huge reallocation.

Attempt mmap-based in-place huge reallocation by plumbing new_addr into
chunk_alloc_mmap().  This can dramatically speed up incremental huge
reallocation.

This resolves #335.

include/jemalloc/internal/chunk_mmap.h

@@ -9,8 +9,8 @@
 /******************************************************************************/
 #ifdef JEMALLOC_H_EXTERNS
 
-void	*chunk_alloc_mmap(size_t size, size_t alignment, bool *zero,
-    bool *commit);
+void	*chunk_alloc_mmap(void *new_addr, size_t size, size_t alignment,
+    bool *zero, bool *commit);
 bool	chunk_dalloc_mmap(void *chunk, size_t size);
 
 #endif /* JEMALLOC_H_EXTERNS */