2013-06-09  Sandra Loosemore  <sandra@codesourcery.com>

	opcodes/
	* nios2-opc.c (nios2_builtin_opcodes): Give "trap" a type-"b"
	argument.

	gas/
	* config/tc-nios2.c (nios2_parse_args):  Allow trap argument to
	omitted.

	gas/testsuite/
	* gas/nios2/trap.s: Add additional test cases for optional
	argument.
	* gas/nios2/trap.d: Likewise.