Blind fix for OPreparedStatement::setParameter's useWChar case

...after 0181a13904daef160bee543e9806b23a835f79c8 "odbc properly support
platform with sizeof(SQLWCHAR) = 4" introduced usage of RTL_TEXTENCODING_UCS2/4
there, which do not make sense in combination with converting between OString
and OUString.

OTools::getStringValue will need a corresponding fix, too, in the other
direction (where the OUString(sal_uInt32 const * codePoints,
sal_Int32 codPointCount) ctor will be useful).

Change-Id: Ia94cd0deec46d269b6ee43362f4849837bb011c5