Address the TODO in the build and unify the libxml2 handling with
LLVM/clang. Use the information now and propagate this into the lit
configuration so that tests can be made aware of libxml2 status.
Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
This commit adds infrastructure for conversion and testing it.
The conversion is still incomplete, pending discussion about which tags should
we use in the XML documents. I copied the RelaxNG schema from Clang, and will
edit it accordingly.
Swift SVN r16451
