PR 20627: Use resume_stop to stop lwp

PR 20627: Use resume_stop to stop lwp

Commit 049a8570 (Use target_continue{,_no_signal} instead of target_resume)
replaces the code stopping lwp with target_continue_no_signal in
target_stop_and_wait, like this,

-  resume_info.thread = ptid;
-  resume_info.kind = resume_stop;
-  resume_info.sig = GDB_SIGNAL_0;
-  (*the_target->resume) (&resume_info, 1);
+  target_continue_no_signal (ptid);

the replacement is not equivalent, and it causes PR 20627.  This patch
is just to revert that change.

Regression testing it on x86_64-linux.

gdb/gdbserver:

2016-09-30  Yao Qi  <yao.qi@linaro.org>

	PR gdbserver/20627
	* target.c (target_stop_and_wait): Don't call
	target_continue_no_signal, use resume_stop instead.