Don't compile some opcodes files when bfd is 32-bit only

	* Makefile.am (TARGET_LIBOPCODES_CFILES): Split into..
	(TARGET64_LIBOPCODES_CFILES): ..this and..
	(TARGET32_LIBOPCODES_CFILES): ..this.
	(ALL_MACHINES): Likewise split to
	(ALL64_MACHINES, ALL32_MACHINES): ..this.
	* disassemble.c: Define some ARCH_* when ARCH_all only if BFD64.
	* configure.ac (BFD_MACHINES): Defined depending on BFD_ARCH_SIZE.
	* Makefile.in: Regenerate.
	* configure: Regenerate.