Do not interrupt on SIGCONT

SIGCONT signals should not interrupt any system calls (locking or wait pid for
example).

BUG=chromium:417800
TEST=build_packages --board=amd64-generic works.
TEST=trybot run on chromiumos-sdk.

Change-Id: Ibb74a60a821e06255d906f85208f85f7f58e08c6
Reviewed-on: https://chromium-review.googlesource.com/220077
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Bertrand Simonnet <bsimonnet@chromium.org>
diff --git a/pym/_emerge/Scheduler.py b/pym/_emerge/Scheduler.py
index d6db311..6e3bf1a 100644
--- a/pym/_emerge/Scheduler.py
+++ b/pym/_emerge/Scheduler.py
@@ -1017,6 +1017,7 @@
 			earlier_sigterm_handler = signal.signal(signal.SIGTERM, sighandler)
 			earlier_sigcont_handler = \
 				signal.signal(signal.SIGCONT, self._sigcont_handler)
+			signal.siginterrupt(signal.SIGCONT, False)
 
 			try:
 				rval = self._merge()