The intent is that (devel flavor) mce will make an attempt to
coredump / kill compositor process that stops responding to
display blank/unblank control ipc - when it is unlikely that
compositor is unresponsive because it has been stopped in
debugger. This feature stopped working after systemd sandboxing
features were taken in use.
Add CAP_SYS_PTRACE - required by debugger detection.
Add CAP_KILL - required for sending signals to unrelated processes.
Add diagnostic logging in error paths of related code.
Signed-off-by: Simo Piiroinen <email@example.com>