* config/alpha/linux.h (OPTION_GLIBC): Define differently if
	SINGLE_LIBC.
	* config/linux.h (OPTION_GLIBC, OPTION_UCLIBC, OPTION_BIONIC):
	Define differently if SINGLE_LIBC.
	* config/rs6000/linux.h (OPTION_GLIBC): Define differently if
	SINGLE_LIBC.
	* config/rs6000/linux64.h (OPTION_GLIBC): Define differently if
	SINGLE_LIBC.
	* config.gcc (*-*-linux* | frv-*-*linux* | *-*-kfreebsd*-gnu |
	*-*-knetbsd*-gnu | *-*-gnu* | *-*-kopensolaris*-gnu): Define
	SINGLE_LIBC instead of OPTION_GLIBC.
	(*-*-uclinux*): Define DEFAULT_LIBC and SINGLE_LIBC.
	(bfin*-uclinux*, moxie-*-uclinux*, m68k-*-uclinux*): Don't define
	DEFAULT_LIBC or use linux.opt.

From-SVN: r168094