FakeVim: Fix Windows build

Standalone FakeVim library fails to build on Windows due to missing
operator+ for "QString" and "const char *" arguments.

This is problem even if using `QT_RESTRICTED_CAST_FROM_ASCII`.

Change-Id: I0ec13d7dfa8ef99d98fa737456d12f16facc5427
Reviewed-by: hjk <hjk@qt.io>

src/plugins/fakevim/fakevimhandler.cpp

@@ -7712,7 +7712,8 @@ void FakeVimHandler::Private::surroundCurrentRange(const Input &input, const QSt
     leaveVisualMode();
 
     if (dotCommand.isEmpty()) { // i.e. we came from normal mode
-        dotCommand = dotCommandFromSubMode(g.submode) + (g.surroundUpperCaseS ? "S" : "s")
+        dotCommand = dotCommandFromSubMode(g.submode)
+                     + QLatin1Char(g.surroundUpperCaseS ? 'S' : 's')
                      + g.dotCommand + input.asChar();
     }