This patch is based on HAVE_ICONV effective fix by minemaz
https://sourceforge.net/tracker/?func=detail&aid=2854571&group_id=2294&atid=102294
This is tested on a JET3 file.
"#include " removed from mdbtools.h,
but it makes that HAVE_ICONV is not effective.
Therefore, it is necessary to include config.h before
including mdbtools.h. For instance, in src/libmdb/file.c
and src/libmdb/iconv.c.
