Tidy up commetning, fix DEBUG and printf for Linux.

2013-01-30  Jeremy Bennett <jeremy.bennett@embecosm.com>

	* arc-tdep.c, arc-tdep.h: Corrected C++ style comments throughout.
	* arc-linux-tdep.c: Corrected C++ style comments throughout.
	(arc_debug): Added extern declaration.
	(next_pc): Replace DEBUG macro, updating print structure. Correct
	argument type for callto regcache_cooked_read_unsigned
	(arc_linux_skip_solib_resolver). Correct types for printf.