x86-64: Zero-extend lower 32 bits displacement to 64 bits

Since the addr32 (0x67) prefix zero-extends the lower 32 bits address to
64 bits, change disassembler to zero-extend the lower 32 bits displacement
to 64 bits when there is no base nor index registers.

gas/

	PR gas/26237
	* testsuite/gas/i386/addr32.s: Add tests for 32-bit wrapped around
	address.
	* testsuite/gas/i386/x86-64-addr32.s: Likewise.
	* testsuite/gas/i386/addr32.d: Updated.
	* testsuite/gas/i386/x86-64-addr32-intel.d: Likewise.
	* testsuite/gas/i386/x86-64-addr32.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-addr32-intel.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-addr32.d: Likewise.

opcodes/

	PR gas/26237
	* i386-dis.c (OP_E_memory): Without base nor index registers,
	32-bit displacement to 64 bits.