Use QString::fill instead of eraseData to force copy-on-write

Author: Lauris Kaplinski

src/ui/webeiddialog.cpp

@@ -292,8 +292,9 @@ QString WebEidDialog::getPin()
     // QString uses QAtomicPointer internally and is thread-safe.
     // There should be only single reference and this is transferred to the caller for safety
     QString ret = pin;
-    eraseData(pin);
-    pin.clear();
+	// Cannot use eraseData because we have to force Qt copy-on-write
+	pin.fill('\0');
+	pin.clear();
     return ret;
 }