(libiberty) uwin macro fix

[Jeffrey A Law]

  In message < Pine.SUN.3.93.990411185606.17312G-100000@modi.xraylith.wisc.edu >y
ou write:
  > Minor fix to change __UWIN__ macro to _UWIN (native compiler defines this
  > but not __UWIN__), and fix a a guard macro for sbrk on win32.
  > 
  > Sun Apr 11 18:50:28 1999  Mumit Khan  <khan@xraylith.wisc.edu>
  > 
  > 	* pexecute.c: Change all references to __UWIN__ to _UWIN.
  > 	* xmalloc.c: Likewise.
  > 	(xcalloc): UWIN has sbrk.
  > 	(xrealloc): Fix guard macro.
Thanks.  Installed.

A nit -- include "-p" when making diffs.  That embeds the function name in
the diff hunks making it easier to match diff hunks with ChangeLog entries.

Thanks,
jeff