[NFC] Normalize some test 'main' signatures

There were 3 tests with 'int main(void)', and 6 with the return type on a different line. I'm about to send a patch for main in tests, and this NFC change is unrelated.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@350770 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/utilities/tuple/tuple.tuple/TupleFunction.pass.cpp

@@ -26,8 +26,7 @@ struct X
     void operator()() {}
 };
 
-int
-main()
+int main()
 {
     X x;
     std::function<void()> f(x);