Fix _LocalProcess.terminate on Windows

[amccarth]

Summary

Some of the signals terminate() was trying to send aren't available on Windows, specifically SIGHUP and SIGCONT. This caused lldbtest.py to crash and leave the processes running. This fix should be behavior-preserving on Mac and Linux.

Note that Windows defines SIGINT, but claims it's not a valid signal to send, thus the try/except.

This fix makes it once again possible to run all LLDB tests on Windows, but I'm still investigating why ninja check-lldb no longer works.

Warning: I'm a Python newbie.

[labath]

lgtm

test/lldbtest.py

class _LocalProcess(_BaseProcess):
     def launch(self, executable, args):
         self._proc = Popen([executable] + args,
                            stdout = open(os.devnull) if not self._trace_on else None,
                            stdin = PIPE)
 
     def terminate(self):
         if self._proc.poll() == None:
             # Terminate _proc like it does the pexpect
-            self._proc.send_signal(signal.SIGHUP)
-            time.sleep(self._delayafterterminate)
-            if self._proc.poll() != None:
-                return
-            self._proc.send_signal(signal.SIGCONT)
-            time.sleep(self._delayafterterminate)
-            if self._proc.poll() != None:
-                return
-            self._proc.send_signal(signal.SIGINT)
+            signals_to_try = [sig for sig in ['SIGHUP', 'SIGCONT', 'SIGINT'] if sig in dir(signal)]
+            for sig in signals_to_try:
+                try:
+                    self._proc.send_signal(getattr(signal, sig))
                     time.sleep(self._delayafterterminate)
                     if self._proc.poll() != None:
                         return
+                except ValueError:
+                    pass  # Windows says SIGINT is not a valid signal to send
             self._proc.terminate()
             time.sleep(self._delayafterterminate)
             if self._proc.poll() != None:
                 return
             self._proc.kill()
             time.sleep(self._delayafterterminate)
 
     def poll(self):