[PATCH] [zorg] Add libc++ and libc++abi builders for Linux.

[Dan Albert]

================
Comment at: zorg/buildbot/builders/LibcxxAndAbiBuilder.py:62
@@ +61,3 @@
+        name='cmake', command=['cmake', '..'], haltOnFailure=True,
+        workdir=build_path, env={'CC': clang, 'CXX': clangxx}))
+
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gribozavr: can I assume there's a relatively recent clang installed on your buildslave?

http://reviews.llvm.org/D4786