Remove unhelpful drop_caps() call in pasta_start_ns()

drop_caps() has a number of bugs which mean it doesn't do what you'd
expect.  However, even if we fixed those, the call in pasta_start_ns()
doesn't do anything useful:

* In the common case, we're UID 0 at this point.  In this case drop_caps()
  doesn't accomplish anything, because even with capabilities dropped, we
  are still privileged.
* When attaching to an existing namespace with --userns or --netns-only
  we might not be UID 0.  In this case it's too early to drop all
  capabilities: we need at least CAP_NET_ADMIN to configure the
  tap device in the namespace.

Remove this call - we will still drop capabilities a little later in
sandbox().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

pasta.c

@@ -224,8 +224,6 @@ void pasta_start_ns(struct ctx *c, int argc, char *argv[])
 		exit(EXIT_FAILURE);
 	}
 
-	drop_caps();
-
 	NS_CALL(pasta_wait_for_ns, c);
 }