Add missing include for signal.h
--- a/lib/cpp/test/TNonblockingSSLServerTest.cpp
+++ b/lib/cpp/test/TNonblockingSSLServerTest.cpp
@@ -30,6 +30,10 @@

 #include <event.h>

+#ifdef __linux__
+#include <signal.h>
+#endif
+
 using namespace apache::thrift;
 using apache::thrift::concurrency::Guard;
 using apache::thrift::concurrency::Monitor;