RFR: JDK-8191204 Post-consolidation cleaning up of the build system

[Tim Bell]

Magnus:

> I think this is the last round of the post-consolidation cleaning up of
> the build system. I'm removing some now-redundant checks, aligning to
> more common calling practice, and speeding up the hg status check (which
> was becoming more urgent as the repo grow in size).
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8191204
> WebRev:
> http://cr.openjdk.java.net/~ihse/JDK-8191204-post-consolidation-cleanup/webrev.01

Looks good.

For make/hotspot/lib/CompileLibjsig.gmk I see there will be a merge with 
the fix for JDK-8190418, but that should be trivial.

Tim