RFR: JDK-8192067 Add fixpath to test image

[Tim Bell]

Magnus:

> To be able to support the use case of running tests using the normal
> make files from prebuilt product and test images, we need to bundle the
> fixpath binary with the test image on Windows.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8192067
> WebRev:
> http://cr.openjdk.java.net/~ihse/JDK-8192067-add-fixpath-to-test-image/webrev.01

Looks good.

Tim