Don't rely on OSX SDK malloc/malloc.h for malloc_zone struct definitions

The SDK jemalloc is built against might be not be the latest for various
reasons, but the resulting binary ought to work on newer versions of
OSX.

In order to ensure this, we need the fullest definitions possible, so
copy what we need from the latest version of malloc/malloc.h available
on opensource.apple.com.

include/jemalloc/internal/jemalloc_internal.h.in

@@ -162,7 +162,6 @@ static const bool have_thp =
 #include <mach/mach_error.h>
 #include <mach/mach_init.h>
 #include <mach/vm_map.h>
-#include <malloc/malloc.h>
 #endif
 
 #include "jemalloc/internal/ph.h"

include/jemalloc/internal/jemalloc_internal_defs.h.in

@@ -243,7 +243,6 @@
  * Darwin (OS X) uses zones to work around Mach-O symbol override shortcomings.
  */
 #undef JEMALLOC_ZONE
-#undef JEMALLOC_ZONE_VERSION
 
 /*
  * Methods for determining whether the OS overcommits.