"call function when asleep" and "send end of file".
* gdb.base/corefile.exp: Add "i*86-*-linuxaout" to xfail list
for "backtrace in corefile.exp".
* gdb.base/a1-selftest.exp: Add "i*86-*-linux*" to xfail list
for "backtrace through signal handler".
* gdb.base/corefile.exp: Make sure we actually generate a core file
before trying the core tests. Some systems allow the user to suppress
generation of core files and default to that (linux for example).
* gdb.base/signals.exp: Change xfail for "next" acting like "continue"
from "i*86-*-linux" to "i*86-*-linuxaout". Works with ELF beta.
