net/czmq: Backport fix for build failure on 8.x

pkg-fallout reported the following build failure on 8.4 (GCC)

src/zactor.c:1: error: stray '\357' in program
src/zactor.c:1: error: stray '\273' in program
src/zactor.c:1: error: stray '\277' in program

Back port the fix [1] removing BOM headers after creating an issue [2]
upstream.

[1] https://github.com/zeromq/czmq/pull/1031
[2] https://github.com/zeromq/czmq/issues/1029

Reported by: pkg-fallout