configure: fix seccomp check Currently, if libseccomp is missing but the user explicitly requested seccomp support using --enable-seccomp, configure silently ignores the situation and disables seccomp support. This is unlike all other tests that explicitly fail in such situation. Fix that. Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Reviewed-by: Andreas Färber <afaerber@suse.de> Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>