busybox

appletlib: avoid warning on unused function ingroup

libbb/appletlib.c:558:12: warning: 'ingroup' defined but
                                   not used [-Wunused-function]
 static int ingroup(uid_t u, gid_t g)
            ^~~~~~~

That function is used only if FEATURE_SUID_CONFIG is also enabled.

Signed-off-by: Cristian Ionescu-Idbohrn <cristian.ionescu-idbohrn@axis.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>