Don't compile non-lib modules as lib modules [BZ #21864]

Some programs have more than one source files.  These non-lib modules
should not be compiled with -DMODULE_NAME=libc.  This patch puts these
non-lib modules in $(others-extras) and adds $(others-extras) to
all-nonlib.

	[BZ #21864]
	* Makerules (all-nonlib): Add $(others-extras).
	* catgets/Makefile (others-extras): New.
	* elf/Makefile (others-extras): Likewise.
	* nss/Makefile (others-extras): Likewise.