Simple input test for Jenkins build.py

Some testing is better than none.  This script will soon be replaced with a real test suite, I will commit this until then. It runs though most of the known configurations of the Jenkins bot.

git-svn-id: https://llvm.org/svn/llvm-project/zorg/trunk@223696 91177308-0d34-0410-b5e6-96231b3b80d8
Formatting fixup

git-svn-id: https://llvm.org/svn/llvm-project/zorg/trunk@223697 91177308-0d34-0410-b5e6-96231b3b80d8
Refactor `derive()` and `derive_lldb()` and add `derive_llvm+clang`

Patch by Duncan Exon Smith <dexonsmith@apple.com>

Refactor `derive()` and `derive_lldb()` to share code and
stop hardcoding expectations.  Although the
exact rsync commands will change slightly (with some
redundant excludes), there should be no effective
functionality change.

Change `check_repo_state()` to log what it finds
instead of giving an error when something is missing.

IMO, the sanity check only provides value on builders
that aren't mature.  Builders that are "working" should
fail in the "acquire" step.  Logging what's going on
seems sufficient.

Another approach would be to thread the set of repos
through the `build()` step, but I think that would be
pretty awkward.

Add `derive-llvm+clang()`: the end goal is to enable
Jenkins to checkout just llvm and clang for a faster
incremental builder

git-svn-id: https://llvm.org/svn/llvm-project/zorg/trunk@223698 91177308-0d34-0410-b5e6-96231b3b80d8