Revert "Fix __getreent function for Cygwin"

This reverts commit 4de8596.  It worked around a problem which was
actually introduced by patch 10a30e7 a few weeks ago.  Rather than
adding special code to the newlib version of __getreent, the followup
patch reinstantiates the original, Cygwin-only implementation of
__getreent.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Stefan Assmann <sassmann@redhat.com>

newlib/libc/reent/getreent.c

@@ -1,4 +1,5 @@
 /* default reentrant pointer when multithread enabled */
+
 #include <_ansi.h>
 #include <reent.h>
 
@@ -9,11 +10,5 @@
 struct _reent *
 _DEFUN_VOID(__getreent)
 {
-#ifdef __CYGWIN__
-  /* Utilize Cygwin's inline definition from include/cygwin/config.h
-     (note the extra underscore) */
-  return __inline_getreent ();
-#else
   return _impure_ptr;
-#endif
 }