sepcomp: do not colorize dead method by default

Thanks to the fix of #375, this optimization is the new default if RTA
is available.

Signed-off-by: Jean Privat <jean@pryen.org>
Merge: sepcomp: do not colorize dead method by default

Thanks to the fix of #375, this optimization is the new default if RTA
is available.

Pull-Request: #452
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>