build: Ease source for AC_LANG_SOURCE of CGRAPH check

diff --git a/configure.ac b/configure.ac
index 7d2c8525909efeccd7ae6c342e020b0ffcff9141..66cbd52a322ab9b395ce0bf60e51b93edba904a4 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -180,7 +180,7 @@ if test x$enable_valadoc = xyes; then
        AC_RUN_IFELSE(
                [AC_LANG_SOURCE([
                        #include <gvc.h>
-                       int main(void) {
+                       int main() {
                                #ifdef WITH_CGRAPH
                                        return 0;
                                #else