* itbl-ops.c: New file. Add support for dynamically read

	* itbl-ops.c: New file.  Add support for dynamically read
	instruction registers, opcodes and formats.  Build internal table
	for new instructions and provide callbacks for assembler and
	disassembler.
	* itbl-lex.l, itbl-parse.y: Lex and yacc parsers for instruction
	spec table.
	* itbl-ops.h: New file.  Header file for itbl support.
	* config/itbl-mips.h: New file.  Mips specific definitions for
	itbl support.