Add a test that runs the ParallelJIT example program to ensure that the

Add a test that runs the ParallelJIT example program to ensure that the
JIT can run against a multi-threaded program without getting its data
structures messed up. Also had to add the examples directory to the path
for the tests so that ParallelJIT can be found.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22415 91177308-0d34-0410-b5e6-96231b3b80d8