Encoding/locale problems in qgtkstyle/native dialogs

qgtkstyle has two bugs in locales other than UTF-8:
1. Qt transmit file dialog's caption to gtk in current locale, but it should do this in utf-8 string.
2. Qt interpret result of file dialog's as UTF-8, but this is string in current locale's encoding.

Both bugs could be easily seen on captions/filenames with non-latin1 symbols.

After my fixes, qgtkstyle works both in UTF-8 and in 8bit (KOI8-R for me) locales.
I could provide tests and screenshots if you need it.

Fixes are available here:
https://qt.gitorious.org/qt/gq-qt/commits/
484d3b7: qgtkstyle: Fix dialog captions in non-UTF8 locales.
774fd3a: qgtkstyle: Fix file dialogs result in non-UTF8 locales.