Don't use ANSI calls in QgisUntwine

[uclaros]

While untwine works ok with accented filenames as a command line tool, it is still failing when run within QGIS on windows.
There problem is the hard coded ANSI variants of windows calls in QgisUntwine_win.cpp (STARTUPINFOA and CreateProcessA).

Reverting the dirty fix from qgis/QGIS@8a94723 and using the generic CreateProcess while expanding the used filenames through untwine::os::toNative() should finally fix the issue.

[abellgithub]

Would it be easier for you to just take this API/startup code and put it in your repo?

[uclaros]

It's probably easier as it is now, we just grab all untwine source and place it in our external dir.
We shouldn't need to tamper with this file again, as it was just broken from the beginning (I mean the CreateProcessA() usage).