Rework the C strings tests to use ASSERT_SAME_TYPE. NFC there. Also change cwchar.pass.cpp to avoid constructing a couple things from zero - since apparently they can be enums in some weird C library. NFC there, either, since the values were never used.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@349522 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/strings/c.strings/cuchar.pass.cpp

@@ -13,6 +13,8 @@
 
 #include <cuchar>
 
+#include "test_macros.h"
+
 int main()
 {
 }