Make memcached setgroups failure non-fatal
Make memcached setgroups failure non-fatal

A call to setgroups can fail on Linux if the user lacks cap_setgid or if setgroups has been disallowed in a user namespace. The latter happens when the namespace has no GID map or if /proc/pid/setgroups has been changed to "deny". Treating this failure as fatal means that memcached cannot start in a bazel fakeroot. Ignoring failure seems harmless.

memcached/memcached,dormando/memcached,memcached/memcached,memcached/memcached,dormando/memcached,memcached/memcached,dormando/memcached,dormando/memcached,memcached/memcached,dormando/memcached