Cleanup ppc code dealing with opcode dumps.

Cleanup ppc code dealing with opcode dumps.

include/
	* opcode/ppc.h (powerpc_num_opcodes): Change type to unsigned.
	(vle_num_opcodes): Likewise.
	(spe2_num_opcodes): Likewise.

opcodes/
	* ppc-opc.c (powerpc_num_opcodes): Likewise.
	(vle_num_opcodes): Likewise.
	(spe2_num_opcodes): Likewise.
	* ppc-dis.c (disassemble_init_powerpc) <powerpc_opcd_indices>: Rewrite
	initialization loop.
	(disassemble_init_powerpc) <vle_opcd_indices>: Likewise.
	(disassemble_init_powerpc) <spe2_opcd_indices>: Likewise.  Initialize
	only once.

gas/
	* config/tc-ppc.c (ppc_setup_opcodes) <powerpc_opcodes>: Rewrite code
	to dump the entire opcode table.
	(ppc_setup_opcodes) <spe2_opcodes>: Likewise.
	(ppc_setup_opcodes) <vle_opcodes>: Likewise.  Fix calculation of
	opcode index.