[RFC] Fix Zero and Shark builds

[Roman Kennke]

First of all, let me tell you how great the new build machinery is: IT
ROCKS! Thanks for doing this!

These changes introduce the necessary configure- and make-foo to make
Zero and Shark builds work with the build-infra machinery. With this,
Zero and Shark builds are as easy as:

bash configure --with-jvm-variants=zero[shark]
make

it will check for existence of libffi and llvm, and use pkg-config and
llvm-config to figure out all required variables. This is basically
adopted from jdk/make/jdk_generic_profile.sh, and now integrated into
the build.

This only contains the source files, not the regenerated configure
scripts:

http://cr.openjdk.java.net/~rkennke/zero-build-infra/webrev.00/

Which brings up an interesting question (not sure if that has been
discussed before). Who is responsible to regenerating the configure
scripts after a change in the sources? Variances between versions of
autotools will like create a mess in the diffs and probably unforeseen
hiccups.

Also, a small change was required to be able to build images:

http://cr.openjdk.java.net/~rkennke/zero-build-infra-jdk/webrev.01/

Opinions? Can I have a bug-ID? Can I push this?

Best regards,
Roman