The app data dir is not set until after Go's init functions have
run, which means that DataDir is inherently racy. Avoid that race
by blocking in DataDir until it is set from Java.
In other words, trade a race condition with a deadlock.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The data dir string is returned to Go as a byte array of the UTF-8
encoded string, but it is not NUL terminated.
Signed-off-by: Elias Naur <mail@eliasnaur.com>