[Bug 48174] wine-mono creates incorrect strings

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=48174

--- Comment #32 from Rafał Mużyło  ---
...oh, well...

Anyhow, on one hand problem 2 seems like something not writing terminating null
byte upon conversion, on the other the deeper I try to dive into mono source,
the more it looks like all those conversions use mono_utf16_to_utf8 or some
derivative, which definitely do write that byte...

So, while the hack from comment 18 does indeed feel wrong, one of the
conversion paths must be missing that '+1'...