Configure: fix build with -Werror=old-style-definition.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

auto/types/sizeof

@@ -25,7 +25,7 @@ $NGX_INCLUDE_UNISTD_H
 $NGX_INCLUDE_INTTYPES_H
 $NGX_INCLUDE_AUTO_CONFIG_H
 
-int main() {
+int main(void) {
     printf("%d", (int) sizeof($ngx_type));
     return 0;
 }

auto/types/typedef

@@ -27,7 +27,7 @@ do
 #include <netinet/in.h>
 $NGX_INCLUDE_INTTYPES_H
 
-int main() {
+int main(void) {
     $ngx_try i = 0;
     return (int) i;
 }

auto/types/uintptr_t

@@ -19,7 +19,7 @@ cat << END > $NGX_AUTOTEST.c
 #include <sys/types.h>
 $NGX_INTTYPES_H
 
-int main() {
+int main(void) {
     uintptr_t i = 0;
     return (int) i;
 }