* tc-pdp11.c: Use VAX float format support for PDP-11 target.

	* tc-pdp11.c: Use VAX float format support for PDP-11 target.
	(parse_ac5): New function for parsing float regs in float operand.
	(parse_expression): Remove attempt to make literals be octal.
	(parse_op_no_deferred): Support float literals.
	(parse_op): Reject attempts to refer to float regs.
	(parse_fop): New function, like parse_op but for float operand.
	(md_assemble): Add cases to parse float operands.  Also fix
	IMM3, IMM6, IMM8 cases to pick up the operand from the right spot.