Qemu: make the qemu_pipe_open back compatible

Commit c7b098ceb528afc62b1545377201e45f5d37f974 has changed
the qemu_pipe_open interface to require the "pipe:" prefix in
the service name.

However in APIs 24 and before, the "pipe:" prefix is not required
This causes quite some confusion and bugs since it is very common
to forget the difference when working across differnet APIs.

This CL is meant to make qemu_pipe_open work in both cases by
doing the following:
1. try the service name as is;
2. if it fails, add 'pipe:' prefix and try the service name again.

Change-Id: If9782396c03780fad1aadeb8374eb308517dc963
(cherry picked from aosp f7d64fd8e1703c54ff01c2e53b0af850977777a0)
2 files changed