hg: jdk/sandbox: Revert some changes back to default.

[magnus.ihse.bursie at oracle.com]

Changeset: e80b1555a540
Author:    ihse
Date:      2020-04-28 21:36 +0200
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/e80b1555a540

Revert some changes back to default.

! make/RunTestsPrebuiltSpec.gmk
! make/autoconf/boot-jdk.m4
! make/gensrc/Gensrc-jdk.internal.vm.compiler.gmk
! make/gensrc/Gensrc-jdk.internal.vm.compiler.management.gmk