[11u] RFR: 8256810: Incremental rebuild broken on Macosx

[Doerr, Martin]

Hi,

JDK-8256810 is backported to 11.0.11-oracle. I'd like to backport it for parity.
Change doesn't apply cleanly because of an unlrelated context change (Solaris removal).

Bug:
https://bugs.openjdk.java.net/browse/JDK-8256810

Original change:
https://github.com/openjdk/jdk/commit/4c86e46d

11u backport:
http://cr.openjdk.java.net/~mdoerr/8256810_build_11u/webrev.00/

Please review.

Best regards,
Martin