Makefile.rtl, [...]: Introduce a "STANDALONE" mode where C runtime files do not have any dependency...

	* Makefile.rtl, expect.c, env.c, aux-io.c, mkdir.c, initialize.c,
	cstreams.c, raise.c, tracebak.c, adadecode.c, init.c, raise-gcc.c,
	argv.c, adaint.c, adaint.h, ctrl_c.c, sysdep.c, rtinit.c, cio.c,
	seh_init.c, exit.c, targext.c: Introduce a "STANDALONE" mode where C
	runtime files do not have any dependency on GCC include files.
	Remove unnecessary includes.
	Remove remaining references to VMS in runtime C file.
	* runtime.h: new File.

From-SVN: r273576