Make dosep correctly invoke the top-level script when forking out

packages/Python/lldbsuite is now a Python package, and it relies
on its __init__.py being called to do package-level initialization.
If you exec packages/Python/lldbsuite/dotest.py directly, you won't
get this package level initialization, and things will fail.  But
without this patch, this is exactly what dosep itself does.  To
launch the multi-processing fork, it was hardcoding a path to
dotest.py and exec'ing it from inside the package.

The fix here is to get the path of the top-level script, and
then exec'ing that instead.  A more robust solution would involve
refactoring the code so that dosep execs some internal script that
imports lldbsuite, but that's a bit more involved.

Differential Revision: http://reviews.llvm.org/D14157
Reviewed by: Todd Fiala

llvm-svn: 251819
diff --git a/lldb/packages/Python/lldbsuite/test/dosep.py b/lldb/packages/Python/lldbsuite/test/dosep.py
index 0342d7e..4f9a23d 100644
--- a/lldb/packages/Python/lldbsuite/test/dosep.py
+++ b/lldb/packages/Python/lldbsuite/test/dosep.py
@@ -279,11 +279,12 @@
     return process_driver.results
 
 
-def process_dir(root, files, test_root, dotest_argv, inferior_pid_events):
+def process_dir(root, files, dotest_argv, inferior_pid_events):
     """Examine a directory for tests, and invoke any found within it."""
     results = []
     for name in files:
-        script_file = os.path.join(test_root, "dotest.py")
+        import __main__ as main
+        script_file = main.__file__
         command = ([sys.executable, script_file] +
                    dotest_argv +
                    ["--inferior", "-p", name, root])
@@ -966,7 +967,7 @@
     test_work_items = []
     find_test_files_in_dir_tree(
         test_subdir, lambda testdir, test_files: test_work_items.append([
-            test_subdir, test_files, test_directory, dotest_argv, None]))
+            test_subdir, test_files, dotest_argv, None]))
 
     # Convert test work items into test results using whatever
     # was provided as the test run function.