Move #include<iconv.h> from common/encoding.h to
common/encoding.cpp and change the methods accordingly.
This resulted in not saving the iconvHandle if using the
"non-static" version of conversion, but it simplified the code
and hopefuly resolved issues with forbidden symbols on some
platforms.
Thil should fix the ds build. For some reason
I thought the forbidden.h wouldn't allow me to
include the iconv.h, so I tryed to include it
before the forbidden.h (it seems like I didn't
have to do that.)