audio: Ignore SIGPIPE in the default audio HAL wrapper

It could happen that a service process receives a SIGPIPE
while providing a dump due unexpected pipe closure on
the other side. This should not lead to a service
termination. Ignoring SIGPIPE is a normal practice for
system services.

Bug: 191123848
Test: adb shell kill -s 13 <pid-of-audio-hal>
Change-Id: I9c1d170b76aa27203206e8fd2ce2fc3f5431baac