Make signal-while-stepping-over-bp-other-thread.exp run against remote targets too.

Make signal-while-stepping-over-bp-other-thread.exp run against remote targets too.

Use pthread_kill instead of the host's "kill".  The reason the test
wasn't written that way to begin with, is that done this way, before
the previous fixes to make GDB step-over all other threads before the
stepping thread, the test would fail...

Tested on x86_64 Fedora 17, native and gdbserver.

gdb/testsuite/
2014-03-20  Pedro Alves  <palves@redhat.com>

	* gdb.threads/signal-while-stepping-over-bp-other-thread.c (main):
	Use pthread_kill to signal thread 2.
	* gdb.threads/signal-while-stepping-over-bp-other-thread.exp:
	Adjust to make the test send itself a signal rather than using the
	host's "kill" command.