MFH: r507639

devel/py-llfuse: Fix build (warning=error), remove -Werror

-Werror is added to flags by default, breaking build for example with GCC.

Follow upstream and remove it. Also disable DEVELOPER_MODE since it's enabled too widely.

PR: 238887
Approved by: portmgr (blanket(s): build fix, ports compliance), linimon (mentor)
Differential Revision: https://reviews.freebsd.org/D21067