Add benchmark for QChar

Add benchmark for QChar

The benchmark isn't exhaustive, but tests the functions
that are heavily used by QtDeclarative.

For performance reasons, QtDeclarative has its own
implementation of various QChar functions (in
qdeclarativeutils_p.h). But we want to make the actual
QChar functions as fast, so that QtDeclarative can also
use them.

Change-Id: Ic25f30651224c39f2824380d679b8500739f38c3
Reviewed-on: http://codereview.qt-project.org/4900
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>