[dotest] Remove test build directories for passing tests

[labath]

Summary

This logic is hooked into the same mechanism as the deletion of log
files, which makes it possible to use the --log-success argument to have
dotest keep the files around (for comparative analysis or whatever).

This makes the --log-successs option slightly misnamed. However one
could argue that the contents of the build folder represents a "log" of
the test's execution, so I chose to to rename it.

packages/Python/lldbsuite/test/lldbtest.py

def getBuildDir(self):
         """Return the full path to the current test."""
         return os.path.join(os.environ["LLDB_BUILD"], self.mydir,
                             self.getBuildDirBasename())
     
      
     def makeBuildDir(self):
         """Create the test-specific working directory, deleting any previous
         contents."""
-        # See also dotest.py which sets up ${LLDB_BUILD}.
+        self.cleanBuildDir()
+        lldbutil.mkdir_p(self.getBuildDir())
+
+    def cleanBuildDir(self):
         bdir = self.getBuildDir()
         if os.path.isdir(bdir):
             shutil.rmtree(bdir)
-        lldbutil.mkdir_p(bdir)
  
     def getBuildArtifact(self, name="a.out"):
         """Return absolute path to an artifact in the test's build directory."""
         return os.path.join(self.getBuildDir(), name)
  
     def getSourcePath(self, name):
         """Return absolute path to a file in the test's source directory."""
         return os.path.join(self.getSourceDir(), name)
def dumpSessionInfo(self):
             file=self.session)
         self.session.close()
         del self.session
 
         # process the log files
         log_files_for_this_test = glob.glob(self.log_basename + "*")
 
         if prefix != 'Success' or lldbtest_config.log_success:
-            # keep all log files, rename them to include prefix
+            # keep all test artifacts, rename log files to include prefix
             dst_log_basename = self.getLogBasenameForCurrentTest(prefix)
             for src in log_files_for_this_test:
                 if os.path.isfile(src):
                     dst = src.replace(self.log_basename, dst_log_basename)
                     if os.name == "nt" and os.path.isfile(dst):
                         # On Windows, renaming a -> b will throw an exception if b exists.  On non-Windows platforms
                         # it silently replaces the destination.  Ultimately this means that atomic renames are not
                         # guaranteed to be possible on Windows, but we need this to work anyway, so just remove the
                         # destination first if it already exists.
                         remove_file(dst)
 
                     os.rename(src, dst)
         else:
-            # success!  (and we don't want log files) delete log files
+            # success!  (and we don't want any artifacts): delete log files and
+            # nuke the build dir.
+            self.cleanBuildDir()
             for log_file in log_files_for_this_test:
                 remove_file(log_file)
 
     # ====================================================
     # Config. methods supported through a plugin interface
     # (enables reading of the current test configuration)
     # ====================================================