Declarative: Compile on Windows.

- Remove UTF8 special characters from comments in qsgcontext2d.cpp.

Change-Id: I7ba71f7db72d6d31dec115483ff785a0ce79d0e2
Reviewed-on: http://codereview.qt-project.org/5738


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Charles Yin <charles.yin@nokia.com>
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>
Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>