Skip attach-many-short-lived-threads.exp on known-broken DejaGnu versions
If the testsuite is run with a DejaGnu version that predates the fix
from last year:
[PATCH] DejaGnu kills the wrong process due to PID-reuse races
http://lists.gnu.org/archive/html/dejagnu/2015-07/msg00005.html
... gdb.threads/attach-many-short-lived-threads.exp fails randomly,
often. Other tests randomly fail due to that issue too, but this one
is _much_ more exposed.
DejaGnu 1.6 was released meanwhile, which includes that DejaGnu fix,
and also some distros backported the fix too.
So skip the test when run with older/broken DejaGnus.
gdb/testsuite/ChangeLog:
2016-05-27 Pedro Alves <palves@redhat.com>
* gdb.threads/attach-many-short-lived-threads.exp (bad_dejagnu):
New procedure.
(top level): Call it, and bail out of DejaGnu is known to be bad.