Fix gas elf/dwarf2-3 testcase for ARM

[Dave Korn]

Kirill A. Shutemov wrote:
> I really don't know why "Minimum Instruction Length" is 2 on ARM.
> Any ideas?.

  Because it's not an x86 and 2 bytes is indeed the length of the minimum
instruction (i.e. in thumb mode)?

    cheers,
      DaveK