[11u] RFR(s): 8236921: Add build target to produce a JDK image suitable for a Graal/SVM build

[Severin Gehwolf]

Hi,

Could I please get a review of this OpenJDK 11u port of JDK-8236921?
This patch is really only for developer convenience who prefer to build
their JDK from source and would like to build svm/graal with the
result. It adds a new make target, 'graal-builder-image' which then
produces an image in <images>/graal-builder-jdk which can be used to
build graal/svm.

This patch depends on the static-images libs backport[1]. Note that
even with that the JDK 15 patch does not apply cleanly because of some
context changes:

 * jcov-image target is not in JDK 11
 * Copyright dates differ in make/Main.gmk and
   make/autoconf/spec.gmk.in.

Fixed both manually.

Bug: https://bugs.openjdk.java.net/browse/JDK-8236921
webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8236921/jdk11u/01/webrev/

Testing: built graal-builder-image target and with the result graal
master. Works fine.

Thanks,
Severin

[1] http://mail.openjdk.java.net/pipermail/jdk-updates-dev/2020-March/002740.html
    Hopefully to be integrated soon.