hg: build-infra/jdk9/hotspot: Rework feature handling to a list of enabled features.

[magnus.ihse.bursie at oracle.com]

Changeset: 541001a907f1
Author:    ihse
Date:      2015-10-09 16:47 +0200
URL:       http://hg.openjdk.java.net/build-infra/jdk9/hotspot/rev/541001a907f1

Rework feature handling to a list of enabled features.

! makefiles/BuildHotspot.gmk
! makefiles/JvmFeatures.gmk
! makefiles/JvmFeaturesConf.gmk
! makefiles/JvmPlatforms.gmk
! makefiles/JvmPlatformsConf.gmk