print-rtl.c (print_rtx): Call PRINT_REG with second argument -1.

	* print-rtl.c (print_rtx): Call PRINT_REG with second argument -1.
	* config/i386/i386.c (print_reg): Abort on a virtual register
	if code != -1; not if file == asm_out_file.
	* config/i386/i386.h (PRINT_REG): Document meaning of CODE == -1.
	(DEBUG_PRINT_REG): Delete, unused.

From-SVN: r73203