Don't drop capability

when some app wants to call /system/bin/ping6 to do something, seccomp
blocks system call--setuid & getuid. remove dropping capability to make
ping6 used. /system/bin/ping doesnot call setuid & getuid, so ping6
is the same behaviour

Bug: 116843590
Test: manual, run app's ping6.ttl, success always
Change-Id: I9e9d45c8e8f049bc11dd652fefff12f79ef24eb6