C++ comments

binutils isn't c99 (yet).  This replaces or removes some C++ style
comments.

bfd/
	* arc-got.h: Use C style comments.
	* coff-z80.c: Likewise.
	* elf32-csky.c: Likewise.
	* peXXigen.c: Likewise.
	* elf32-m32c.c (m32c_elf_relax_delete_bytes): Remove commented out
	code.
binutils/
	* dwarf.c: Use C style comments.
	* resrc.c: Likewise.
gas/
	* config/tc-s12z.c: Use C style comments.
	* config/tc-z80.c: Likewise.
	* config/tc-xtensa.c (emit_ld_r_n): Remove commented out code.
include/
	* coff/internal.h: Use C style comments.
	* coff/pe.h: Likewise.
	* elf/ppc64.h: Likewise.
opcodes/
	* arm-dis.c: Use C style comments.
	* cr16-opc.c: Likewise.
	* ft32-dis.c: Likewise.
	* moxie-opc.c: Likewise.
	* tic54x-dis.c: Likewise.
	* s12z-opc.c: Remove useless comment.
	* xgate-dis.c: Likewise.