[#3351] Fixed leak in signal test

Author: fxdupont

src/lib/asiolink/tests/io_service_signal_unittests.cc

@@ -63,6 +63,9 @@ class IOSignalTest : public ::testing::Test {
     ~IOSignalTest() {
         io_signal_set_.reset();
         // Make sure the cancel handler for the IOSignalSet is called.
+        if (io_service_->stopped()) {
+            io_service_->restart();
+        }
         io_service_->poll();
     }