try to generate a core dump signaling again the thread

lib/ProxySQL_GloVars.cpp

@@ -23,6 +23,13 @@ void crash_handler(int sig) {
 
 	fprintf(stderr, "Error: signal %d:\n", sig);
 	backtrace_symbols_fd(arr, s, STDERR_FILENO);
+#ifdef SYS_gettid
+	// try to generate a core dump signaling again the thread
+	signal(sig, SIG_DFL);
+	pid_t tid;
+	tid = syscall(SYS_gettid);
+	kill(tid, sig);
+#endif /* SYS_gettid */
 	exit(EXIT_FAILURE);
 }