[libcxx] [test] Remove nonportable locale assumption in basic.ios.members/narrow.pass.cpp

[BillyONeal]

Summary

I'm not sure if libcxx is asserting UTF-8 here; but on Windows the full char value is always passed through in its entirety, since the default codepage is something like Windows-1252. The replacement character is only used for non-chars there; and that should be a more portable test everywhere.

[BillyONeal]

Committed r339213

(If there are changes requested I'll do them in a follow up commit)

[BillyONeal]

Adding ldionne as suggested by Eric.

[ldionne]

LGTM and has been committed -- you can close this.

test/std/input.output/iostreams.base/ios/basic.ios.members/narrow.pass.cpp

 
 // char narrow(char_type c, char dfault) const;
 
 #include <ios>
 #include <cassert>
 
 int main()
 {
-    const std::ios ios(0);
-    assert(ios.narrow('c', '*') == 'c');
-    assert(ios.narrow('\xFE', '*') == '*');
+    const std::wios ios(0);
+    assert(ios.narrow(L'c', '*') == 'c');
+    assert(ios.narrow(L'\u203C', '*') == '*');
 }