Unlike many other architectures, x86 does not share an opcode table
between assembly and disassembly. Any consumer of libopcodes would only
ever access one of the two.
1: instantiate i386_{op,reg}tab[] in gas instead of in libopcodes
2: remove i386-opc.c
3: break gas dependency on libopcodes
4: drop sentinel from i386_optab[]
Jan