The extract_stdout_keyvalue() function now accepts an optional delimiter
argument, to override its default of ':'. This makes it useful for extracting
the output of "servald config get" commands.
Fixes#21. The problem was caused when the double-fork logic used in "servald
start" was clobbered in 5103176. This meant that the servald daemon process on
Android no longer had a PPID=1, but the PID of the long-lived
"org.servalproject" parent process which called the JNI entry point. Killing
the servald process then caused it to become a zombie process, since the
org.servalproject does not habitually call wait(2). That caused the "servald
stop" logic to send five SIGHUPs to the zombie without any error, making it
appear that the process was not dying.
Reinstated the double-fork logic and added a new test case to ensure that the
daemon process does not become a zombie on being killed prematurely.
