diff: fix bug 613 (diff -ub segfaults)

function                                             old     new   delta
dump_unified_vec                                     435     457     +22
diff_main                                            855     860      +5
diffreg                                             1786    1781      -5
do_diff                                              428     416     -12
change                                               325     283     -42
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(add/remove: 0/0 grow/shrink: 2/3 up/down: 27/-59)            Total: -32 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed