libftdi: add PACKAGECONFIG for cpp-wrapper

* also fixes
  WARNING: QA Issue: libftdi: The compile log indicates that host include and/or library paths were used.
           Please check the log '/OE/oe-core/tmp-eglibc/work/x86_64-oe-linux/libftdi/0.19-r1/temp/log.do_compile' for more information.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>