smaller code for shift-by-1 on i386

[Jeffrey A Law]

  In message < 39087620.A95C7FE7@BitWagon.com >you write:
  > The i386 has two opcodes 0xD0 and 0xD1 which shift by 1,
  > but they never appear in object files compiled from C/C++ source by gcc.
[ ... ]
I forwarded your message to someone that does a lot of ia32 gas work.

I'd rather attack this in gas so that we don't have to hope that other
assemblers accept an implicit shift count.

Thanks for the bug report.

jeff