RFR: JDK-8188910: jib configure requires --src-dir for out fo tree builds, second attempt

[Erik Joelsson]

Please review my second attempt at fixing this issue. The last time a 
bug in Jib caused problems on Windows. This has now been fixed so we can 
apply this patch again.

Bug: https://bugs.openjdk.java.net/browse/JDK-8188910
Webrev: http://cr.openjdk.java.net/~erikj/8188910/webrev.01/

/Erik