Reusing constant

(cherry picked from commit f91e800402c8e4869eb15068be8f726b603920ba)

Source commit: 37f231decd965ce798b441e443a5cb4c1fa3ad9c

source/core/RemoteFiles.cpp

@@ -91,7 +91,7 @@ UnicodeString __fastcall UnixExtractFileDir(const UnicodeString Path)
   }
   else
   {
-    return (Pos == 1) ? UnicodeString(L"/") : UnicodeString();
+    return (Pos == 1) ? UnicodeString(ROOTDIRECTORY) : UnicodeString();
   }
 }
 //---------------------------------------------------------------------------