multimedia/dvb-apps: Remove references to CA_SET_PID syscall which was
deleted in Linux Kernel 4.14. This fixes a build issue with the upcoming
v4l 1.18.0 update.

PR: 245501
Obtained from: https://gitweb.gentoo.org/repo/gentoo.git/commit/media-tv/linuxtv-dvb-apps/?id=ed58fb83ffaf70423a83866a738978cc273f877b