This imports readline 7.0 (up to patch 5) while preserving all
gdb-local changes.
This was done by checking out the readline git repository, making a
branch based on the gdb baseline revision, applying the gdb changes to
that branch, and then merging from readline 7.
readline/ChangeLog.gdb
2019-08-12 Tom Tromey <tom@tromey.com>
* Imported readline 7.0 patch 5.
775e241e9c