don't force dropping capabilities in lxc-init

don't force dropping capabilities in lxc-init

Commit 0af683cf added clearing of capabilities to lxc-init, but only
after lxc_setup_fs() was done, likely so that the mounting done in
that routine wouldn't fail.

However, in my testing lxc_caps_reset() wasn't really effective
anyway since it did not clear the bounding set. Adding prctl
PR_CAPBSET_DROP in a loop from 0 to CAP_LAST_CAP would fix this, but I
don't think its necessary to forcefully clear all capabilities since
users can now specify lxc.cap.keep = none to drop all capabilities.

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>