X_OK redefinition protection for Cygwin.

[Earnie Boyd]

2001-04-19  Earnie Boyd  <earnie@users.sourceforge.net>

	* include/sys/unistd.h (X_OK): Remove redefinition warnings when 
	including both sys/unistd.h and Cygwin's sys/file.h. 

Index: unistd.h
===================================================================
RCS file: /cvs/src/src/newlib/libc/include/sys/unistd.h,v
retrieving revision 1.20
diff -u -p -r1.20 unistd.h
--- unistd.h	2001/04/13 15:37:47	1.20
+++ unistd.h	2001/04/19 14:50:31
@@ -128,6 +128,7 @@ int     _EXFUN(readlink, (const char *__
 int     _EXFUN(symlink, (const char *__name1, const char *__name2));
 #endif
 
+#ifndef F_OK
 # define	F_OK	0
 # define	R_OK	4
 # define	W_OK	2
@@ -138,6 +139,7 @@ int     _EXFUN(symlink, (const char *__n
 # define X_OK	_cygwin_X_OK
 extern const unsigned _cygwin_X_OK;
 #endif
+#endif /* ndef F_OK */
 
 # define	SEEK_SET	0
 # define	SEEK_CUR	1