config:
	* alpha/gnu.h: Undef TARGET_OS_CPP_BUILTINS.
	* i386/beos-elf.h: Use TARGET_OS_CPP_BUILTINS rather than
	CPP_PREDEFINES and part of CPP_SPEC.
	i386/freebsd-aout.h, i386/gas.h, i386/gnu.h, i386/linux-aout.h,
	i386/linux.h, i386/moss.h, i386/xm-vsta.h: Similarly.

From-SVN: r54286