Alexandre Oliva found a bug in gdb's handling of fixed-point -- a
certain Ada fixed-point type would be misintepreted. The bug was that
the DW_AT_small looked like:
<1><13cd>: Abbrev Number: 16 (DW_TAG_constant)
<13ce> DW_AT_GNU_numerator: 1
<13cf> DW_AT_GNU_denominator: 0x8000000000000000
... but gdb interpreted the denominator as a negative value.