Add "-c 1" to ping6 in test-network-all

Fixes bug 19008. bugfix on 0.2.7.3-rc

Makefile.am

@@ -106,7 +106,7 @@ test-network: need-chutney-path all
 test-network-all: need-chutney-path all test-driver
 	mkdir -p $(TEST_NETWORK_ALL_LOG_DIR)
 	@flavors="$(TEST_CHUTNEY_FLAVORS)"; \
-	if ping6 -q -o ::1 >/dev/null 2>&1; then \
+	if ping6 -q -c 1 -o ::1 >/dev/null 2>&1; then \
 		echo "ping6 ::1 succeeded, running IPv6 flavors: $(TEST_CHUTNEY_FLAVORS_IPV6)."; \
 		flavors="$$flavors $(TEST_CHUTNEY_FLAVORS_IPV6)"; \
 	else \

changes/bug19008

@@ -0,0 +1,3 @@
+  o Major bugfixes (testing):
+    - Fix a bug that would block 'make test-network-all' on systems
+      where IPv6 packets were lost. Fixes bug 19008; bugfix on tor-0.2.7.3-rc.