crtdll.h: Define EXTRA_OS_CPP_BUILTINS.

	* config/i386/crtdll.h: Define EXTRA_OS_CPP_BUILTINS.
	Don't use CPP_PREDEFINES.
	* config/i386/cygwin.h (EXTRA_OS_CPP_BUILTINS): New.
	Used TARGET_OS_CPP_BUILTINS in preference to CPP_PREDEFINES.
	* config/i386/djgpp.h, config/i386/i386-coff.h,
	config/i386/i386-interix.h, config/i386/i386-interix3.h,
	config/i386/lynx-ng.h, config/i386/lynx.h, config/i386/mingw32.h,
	config/i386/openbsd.h, config/i386/ptx4-i.h, config/i386/sysv3.h,
	config/i386/uwin.h: Similarly.

From-SVN: r55101