tests: Fix warnings about unused parameters.

tests/example.c

@@ -17,15 +17,17 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <errno.h>
 
+#include "../src/compiler.h"
 
-int main(int argc, char **argv) {
-    (void)argv;
 
+int main(int argc, char **argv unused) {
     fprintf(stderr, "write to stderr: %d\n", argc);
     printf("write to stdout\n");
     fflush(stdout);

tests/example_error.c

@@ -17,12 +17,17 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #define _GNU_SOURCE /* for program_invocation_name */
 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>
 #include <error.h>
 
+#include "../src/compiler.h"
+
+
 void (*error_print_progname)(void);
 
 
@@ -31,7 +36,7 @@ static void print_prognmae(void) {
 }
 
 
-int main(int argc, char **argv) {
+int main(int argc unused, char **argv unused) {
     program_invocation_name = "./example_error";
 
     error(0, 0, "<message>");

tests/example_exec.c

@@ -17,11 +17,15 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
+#include "../src/compiler.h"
+
 
 #define MAGIC "@RUN_"
 #define MAGIC_LENGTH (strlen(MAGIC))
@@ -75,7 +79,7 @@ static void dump(char *argv[]) {
 }
 
 
-int main(int argc, char **argv) {
+int main(int argc unused, char **argv) {
     char argv0[strlen(argv[0]) + MAGIC_LENGTH + 3 + 1];
 
     char *old_ldpreload = getenv("LD_PRELOAD");

tests/example_vfork.c

@@ -17,12 +17,17 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>
 #include <unistd.h>
 
-int main(int argc, char **argv) {
+#include "../src/compiler.h"
+
+
+int main(int argc unused, char **argv unused) {
     pid_t pid;
 
     fprintf(stderr, "Before vfork().\n");