Fix gcc-4.9 new compile error in tc-m68k.c in gas.
    
    Ignore this:
    
    ../../binutils-2.24/gas/config/tc-m68k.c: In function 'md_assemble':
    ../../binutils-2.24/gas/config/tc-m68k.c:4516:36: error: array subscript is below array bounds [-Werror=array-bounds]
       n = (the_ins.numo - the_ins.fragb[n - 1].fragoff);
    
    which is caught by gcc-4.9 and not by gcc-4.8