hg: build-infra/jdk9/hotspot: Add initial support for aarch64. Also restructure linux part in Common to be more like other platforms.

[magnus.ihse.bursie at oracle.com]

Changeset: ceb1a85c1550
Author:    ihse
Date:      2015-10-01 15:13 +0200
URL:       http://hg.openjdk.java.net/build-infra/jdk9/hotspot/rev/ceb1a85c1550

Add initial support for aarch64. Also restructure linux part in Common to be more like other platforms.

! makefiles/Common.gmk
! makefiles/GensrcAdlc.gmk