Necessary functions are not implemented properly on many Android platforms.
The wrapper converts wchr_t* string to char* one and uses char* functions,
which Android supports well.
This modification is done mostly for Android port of the plugin.
Boost::filesystem replaced by osal-files collection of filesystem functions.
osal-files copied from mupen64plus-video-rice and modified to work with wchar_t strings.
Windows implementation should work well with unicode strings, because
Microsoft provides wide string compatible filesystem functions.
Unix implementation fakes work with unicode strings by converting them to multibyte strings.
It may not work if user will chose folder with non-ASCII path.
