fakeroot: fix build when libcap-dev is installed

Fixes https://bugs.busybox.net/show_bug.cgi?id=8541



Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Tested-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>