Don't optimize the returned length for surrogate-less case, this does save a pass of the string but at the price of returning a wrong result, which is not worth it, just compute the really required length exactly. Closes #16298. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76618 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775