Add a Python script to invoke each test file under the test root using a separate process.

Example:

[11:33:09] johnny:/Volumes/data/lldb/svn/trunk/test $ ./dosep.ty -o "-v -n"
dotest.py options: -v -n
Running /Volumes/data/lldb/svn/trunk/test/dotest.py -v -n -p TestPublicAPIHeaders.py /Volumes/data/lldb/svn/trunk/test/api/check_public_api_headers
1: test_sb_api_directory (TestPublicAPIHeaders.SBDirCheckerCase)
   Test the SB API directory and make sure there's no unwanted stuff. ... ok

----------------------------------------------------------------------
Ran 1 test in 4.404s

OK
Running /Volumes/data/lldb/svn/trunk/test/dotest.py -v -n -p TestEmulations.py /Volumes/data/lldb/svn/trunk/test/arm_emulation
1: test_arm_emulations (TestEmulations.ARMEmulationTestCase) ... ok
2: test_thumb_emulations (TestEmulations.ARMEmulationTestCase) ... ok

----------------------------------------------------------------------
Ran 2 tests in 1.399s

OK

...

llvm-svn: 143355