textproc/ibus: avoid generating "*.cpython3*.opt-2.pyc" by -OO on byte compiling

It unnecessary touch and rebuild setuptools component:

>> Error: Filesystem touched during stage (files must install to ${STAGEDIR}):

extra: usr/local/lib/python3.12/site-packages/_distutils_hack/__pycache__/__init__.cpython-312.opt-2.pyc

Reported by: bulk -t
Approved by: portmgr blanket