This commit adds support for ThreadSanitizer to ctest. ThreadSanitizer
is part of the clang compiler and also gcc 4.8 and later. You have to
compile the code with special flags. Then your code gets the the
ThreadSanitizer ability built into it. To pass options to the
ThreadSanitizer you use an environment variable. This commit teaches
ctest to parse the output from ThreadSanitizer and send it to CDash.
Bill Hoffman