Return error in mosquitto_pub -l if compiled without threading.

client/pub_client.c

@@ -336,6 +336,14 @@ int main(int argc, char *argv[])
 	password = cfg.password;
 	quiet = cfg.quiet;
 
+#ifndef WITH_THREADING
+	if(cfg.pub_mode == MSGMODE_STDIN_LINE){
+		fprintf(stderr, "Error: '-l' mode not available, threading support has not been compiled in.\n");
+		free(buf);
+		return 1;
+	}
+#endif
+
 	if(cfg.pub_mode == MSGMODE_STDIN_FILE){
 		if(load_stdin()){
 			fprintf(stderr, "Error loading input from stdin.\n");

config.mk

@@ -194,6 +194,7 @@ endif
 ifeq ($(WITH_THREADING),yes)
 	LIB_LIBS:=$(LIB_LIBS) -lpthread
 	LIB_CFLAGS:=$(LIB_CFLAGS) -DWITH_THREADING
+	CLIENT_CFLAGS:=$(CLIENT_CFLAGS) -DWITH_THREADING
 endif
 
 ifeq ($(WITH_SOCKS),yes)