Fix missing progname string in 'Usage' message

tests/bandwidth-client.c

@@ -65,7 +65,7 @@ int main(int argc, char *argv[])
             use_backend = RTU;
             n_loop = 100;
         } else {
-            printf("Usage:\n  %s [tcp|rtu] - Modbus client to measure data bandwith\n\n");
+            printf("Usage:\n  %s [tcp|rtu] - Modbus client to measure data bandwith\n\n", argv[0]);
             exit(1);
         }
     } else {

tests/bandwidth-server-one.c

@@ -43,7 +43,7 @@ int main(int argc, char *argv[])
         } else if (strcmp(argv[1], "rtu") == 0) {
             use_backend = RTU;
         } else {
-            printf("Usage:\n  %s [tcp|rtu] - Modbus client to measure data bandwith\n\n");
+            printf("Usage:\n  %s [tcp|rtu] - Modbus client to measure data bandwith\n\n", argv[0]);
             exit(1);
         }
     } else {

tests/unit-test-client.c

@@ -51,7 +51,7 @@ int main(int argc, char *argv[])
         } else if (strcmp(argv[1], "rtu") == 0) {
             use_backend = RTU;
         } else {
-            printf("Usage:\n  %s [tcp|rtu] - Modbus client for unit testing\n\n");
+            printf("Usage:\n  %s [tcp|rtu] - Modbus client for unit testing\n\n", argv[0]);
             exit(1);
         }
     } else {

tests/unit-test-server.c

@@ -47,7 +47,7 @@ int main(int argc, char*argv[])
         } else if (strcmp(argv[1], "rtu") == 0) {
             use_backend = RTU;
         } else {
-            printf("Usage:\n  %s [tcp|rtu] - Modbus server for unit testing\n\n");
+            printf("Usage:\n  %s [tcp|rtu] - Modbus server for unit testing\n\n", argv[0]);
             return -1;
         }
     } else {