procd: Always tell cmake whether to include seccomp support or not

procd: Always tell cmake whether to include seccomp support or not

Without this change, when a user disables seccomp support in .config,
procd does not get recompiled unless the package is cleaned manually.
It is because when -D option is missing from cmake command line, cmake
uses cached value from the previous run where seccomp was enabled.

Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>