Fix problems generating and installing PDF.

2013-03-27  Simon Cook  <simon.cook@embecosm.com>

	* newlib/libc/sys/arc/Makefile.am: Add empty pdf and install-pdf
	targets.
	* newlib/libc/machine/arc/Makefile.am: Likewise.
	* newlib/libc/sys/arc/Makefile.in: Regenerate.
	* newlib/libc/machine/arc/Makefile.in: Likewise.