* gdb.base/interrupt.exp: Setup "i*86-*-linux" xfail for

	* gdb.base/interrupt.exp: Setup "i*86-*-linux" xfail for
	"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.