Fix handling of abstract Unix socket addresses
Fix handling of abstract Unix socket addresses

* Don't truncate abstract addresses at second null.
* Properly handle abstract addresses with length < 108 bytes.

PiperOrigin-RevId: 209502703
Change-Id: I49053f2d18b5a78208c3f640c27dbbdaece4f1a9

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor