S12Z: GAS: New option --mdollar-hex.

S12Z: GAS: New option --mdollar-hex.

This option (also implied by --traditional) causes '$' to introduce
literal hexadecimal constants, rather than the modern convention '0x'.

gas/
	* config/tc-s12z.c (s12z_strtol): New function. (md_show_usage): Update.
	(md_parse_option): new case OPTION_DOLLAR_HEX. (s12z_init_after_args):
	(<global>): Use s12z_strtol instead of strtol.
	* doc/c-s12z.texi (S12Z Options): Document new option -mdollar-hex.
	* testsuite/gas/s12z/dollar-hex.d: New file.
	* testsuite/gas/s12z/dollar-hex.s: New file.
	* testsuite/gas/s12z/s12z.exp: Add them.