Remove redundant void argument lists

Using clang-tidy's `modernize-redundant-void-arg`.
https://clang.llvm.org/extra/clang-tidy/checks/modernize-redundant-void-arg.html

main/tests/test_string.cpp

@@ -1129,7 +1129,7 @@ bool test_35() {
 	return state;
 }
 
-typedef bool (*TestFunc)(void);
+typedef bool (*TestFunc)();
 
 TestFunc test_funcs[] = {