Merge changes Ieef54d84,Ica3e88c2

* changes:
  Remove NetworkStack dependencies on hidden members
  Expose ServiceSpecificException as @SystemApi.

diff --cc api/system-current.txt
Simple merge

diff --cc api/test-current.txt
Simple merge

diff --cc services/net/java/android/net/dhcp/DhcpClient.java
Simple merge

diff --cc services/net/java/android/net/ip/IpClient.java
Simple merge