Fixed history in gdb

[Tom Tromey]

>>>>> "Andrew" == Andrew Burgess <aburgess@redhat.com> writes:

Andrew> Does using the GDB command:
Andrew>   (gdb) set history remove-duplicates 1
Andrew> achieve what you want?

TIL

I sort of think this would be a good feature to add to readline so the
setting can be managed in .inputrc.

Tom