Remove trailing whitespace in test suite. Approved by Marshall Clow.

llvm-svn: 271435

libcxx/test/std/experimental/string.view/string.view.cons/from_string1.fail.cpp

@@ -22,7 +22,7 @@ struct dummy_char_traits : public std::char_traits<char> {};
 int main () {
     using string_view = std::experimental::basic_string_view<char>;
     using string      = std::              basic_string     <char, dummy_char_traits>;
-    
+
     {
     string s{"QBCDE"};
     string_view sv1 ( s );