0.8.21.32: improvement for the space reservation mechanism on OS X

0.8.21.32: improvement for the space reservation mechanism on OS X
  * The C runtime is no longer relinked after running nm, which should avoid
    some cases where symbols moved when linking in the read-only space reservation
	object. This was previously observed as segfaults in target-2 and could be worked
	around by choosing a different C compiler.
  * Space is now reserved for each of our fixed-address spaces on OS X, currently:
      * read-only space
	  * static space
	  * dynamic-1 and dynamic-2 spaces
	  * linkage table space
	Should Apple ever decide to move the malloc heap again, none of these spaces will be picked
	because their virtual memory ranges will have been reserved by the linker.