I found that ME_MakeStringB was previously unused, and that the other
ME_MakeString functions repeated code that was already in ME_MakeStringB.
Making ME_MakeStringB static and using it to avoid duplicate code seemed
like a better idea than removing the function.

Previously it found the start or end by traversing the linked lists of
run, rows, paragraphs, and cells from the current position of the
cursors.  Clearly it is better to get the start or end directly to make
it a constant time operation.

Wrapping is needed to be done even when repainting isn't done since
later messages expect line breaks to reflect the current text.  Some
message can specify not to paint the sceen, but this should prevent
wrapping from being done.

cryptui: Ensure a certificate's private key is exportable before allowing it to be selected for export.

cryptui: Skip password page when moving backward through the export wizard if it wasn't shown in the first place.

- A HWND can be safely marshaled over a LONG as its payload is not
  a pointer but a user handle.
- Use GetWindowLongPtr instead of GetWindowLong to retrieve a pointer.

Relaxing the tests on older versions of Windows caused a couple tests
to fail on more recent ones, which was unintended.

winebuild should be able to find them on its own.