* dbus/dbus-spawn.c, dbus/dbus-spawn.h: Change dbus_spawn to
return a "babysitter" object that is used to monitor the status of
the spawned process and reap it when required.
* test/test-segfault.c, test/test-exit.c,
test/test-sleep-forever.c: binaries that do various lame things,
used in the test suite.
* dbus/dbus-sysdeps.c: kill _dbus_errno_to_string()
