Shrink the size of the x86_insn_info structure, particularly on 64-bit

Shrink the size of the x86_insn_info structure, particularly on 64-bit
systems, by combining operand lists into a single array (and trying to find
overlaps where possible).  This saves about 4K even on a 32-bit system.

Also shrink the generated gperf code by outputting the number of info
structures directly rather than using NELEMS().

svn path=/trunk/yasm/; revision=1943