infrun: Fix TARGET_WAITKIND_NO_RESUMED handling in non-stop mode

Running the testsuite against gdbserver with "maint set target-non-stop on"
stumbled on a set of problems.  See code comments for details.

This handles my concerns expressed in PR14618.

gdb/ChangeLog:
2015-11-30  Pedro Alves  <palves@redhat.com>

	PR 14618
	* infrun.c (handle_no_resumed): New function.
	(handle_inferior_event_1) <TARGET_WAITKIND_NO_RESUMED>: Defer to
	handle_no_resumed.