More "Program" -> "Thread NN received signal" testsuite adjustment

More "Program" -> "Thread NN received signal" testsuite adjustment

These tests should have been adjusted by f303dbd60d9c (Fix PR
threads/19422 - show which thread caused stop), but clearly I had
missed grepping for potential-fail cases.

gdb/testsuite/ChangeLog
2016-03-09  Pedro Alves  <palves@redhat.com>

	* gdb.threads/attach-into-signal.exp: Adjust to "Program received
	signal" -> "Thread NN received signal" output change.
	* gdb.threads/ia64-sigill.exp: Likewise.
	* gdb.threads/linux-dp.exp: Likewise.
	* gdb.threads/manythreads.exp: Likewise.
	* gdb.threads/pending-step.exp: Likewise.
	* gdb.threads/print-threads.exp: Likewise.
	* gdb.threads/sigstep-threads.exp: Likewise.
	* gdb.threads/staticthreads.exp: Likewise.
	* gdb.threads/tls.exp: Likewise.