[binutils-gdb] Revert "Remove true and false ARI checks now that we use stdbool.h."

[sergiodj+buildbot@redhat.com]

*** TEST RESULTS FOR COMMIT 00e474c2e96f9a56f128ee29fbdc36ac32d5e14a ***

Author: Joel Brobecker <brobecker@adacore.com>
Branch: master
Commit: 00e474c2e96f9a56f128ee29fbdc36ac32d5e14a

Revert "Remove true and false ARI checks now that we use stdbool.h."
As we cannot use type bool until conversion to C++ is official,
this patch re-instates the ARI checks for "true/false".

gdb/ChangeLog:

        * contrib/ari/gdb_ari.sh: Reinstate checks for "true" and "false".