How to convert (char *) from ISO-8859-1 to UTF-8 in C++ multiplatformly?

Я меняю программное обеспечение на C ++, которое обрабатывает тексты в формате ISO Latin 1, для хранения данных в базе данных в SQLite.
The problem is that SQLite works in UTF-8... and the Java modules that use same database work in UTF-8.

I wanted to have a way to convert the ISO Latin 1 characters to UTF-8 characters before storing in the database. I need it to work in Windows and Mac.

I heard ICU would do that, but I think it's too bloated. I just need a simple convertion system(preferably back and forth) for these 2 charsets.

How would I do that?