Add Cygwin/MinGW -posix option from specs to i386/cygming.opt

[Joseph S. Myers]

In preparation for the driver only accepting options listed in .opt
files, and not other options that simply happen to match some spec,
this patch adds the -posix option from specs in i386/cygwin.h,
i386/mingw-w64.h and i386/mingw32.h to i386/cygming.opt.

Tested building cc1 and xgcc for crosses to: i686-cygwin i686-mingw32
x86_64-mingw32.  OK to commit?

2011-01-31  Joseph Myers  <joseph@codesourcery.com>

	* config/i386/cygming.opt (posix): New Driver option.

Index: gcc/config/i386/cygming.opt
===================================================================
--- gcc/config/i386/cygming.opt	(revision 169317)
+++ gcc/config/i386/cygming.opt	(working copy)
@@ -1,6 +1,6 @@
 ; Cygwin- and MinGW-specific options.
 
-; Copyright (C) 2005, 2007, 2009, 2010 Free Software Foundation, Inc.
+; Copyright (C) 2005, 2007, 2009, 2010, 2011 Free Software Foundation, Inc.
 ;
 ; This file is part of GCC.
 ;
@@ -49,3 +49,6 @@ Use the GNU extension to the PE format f
 muse-libstdc-wrappers
 Target Condition({defined (USE_CYGWIN_LIBSTDCXX_WRAPPERS)})
 Compile code that relies on Cygwin DLL wrappers to support C++ operator new/delete replacement
+
+posix
+Driver

-- 
Joseph S. Myers
joseph@codesourcery.com