[tools] Properly handle sigterm in gcmole

Bug: chromium:706763
Change-Id: Iac91fa538ed61d1c47509f990ee9426b0b3bdc1d
Reviewed-on: https://chromium-review.googlesource.com/467147Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44401}

tools/gcmole/run-gcmole.py

@@ -4,6 +4,7 @@
 # found in the LICENSE file.
 
 import os
+import signal
 import subprocess
 import sys
 
@@ -16,8 +17,19 @@ BASE_PATH = os.path.dirname(os.path.dirname(GCMOLE_PATH))
 
 assert len(sys.argv) == 2
 
-sys.exit(subprocess.call(
+proc = subprocess.Popen(
     [LUA, DRIVER, sys.argv[1]],
     env={'CLANG_BIN': CLANG_BIN, 'CLANG_PLUGINS': CLANG_PLUGINS},
     cwd=BASE_PATH,
-))
+)
+
+def handle_sigterm(*args):
+  try:
+    proc.kill()
+  except OSError:
+    pass
+
+signal.signal(signal.SIGTERM, handle_sigterm)
+
+proc.communicate()
+sys.exit(proc.returncode)