buildman: Tidy up a few comments

Add some function comments which are missing, or missing arguments.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/buildman/builderthread.py

@@ -91,8 +91,12 @@ class BuilderThread(threading.Thread):
         thread_num: Our thread number (0-n-1), used to decide on a
             temporary directory. If this is -1 then there are no threads
             and we are the (only) main process
+        mrproper: Use 'make mrproper' before each reconfigure
+        per_board_out_dir: True to build in a separate persistent directory per
+            board rather than a thread-specific directory
+        test_exception: Used for testing; True to raise an exception instead of
+            reporting the build result
     """
-    def __init__(self, builder, thread_num, mrproper, per_board_out_dir):
         """Set up a new builder thread"""
         threading.Thread.__init__(self)
         self.builder = builder

tools/buildman/control.py

@@ -124,6 +124,8 @@ def DoBuildman(options, args, toolchains=None, make_func=None, boards=None,
                 arguments. This setting is useful for tests.
         board: Boards() object to use, containing a list of available
                 boards. If this is None it will be created and scanned.
+        clean_dir: Used for tests only, indicates that the existing output_dir
+            should be removed before starting the build
     """
     global builder
 

tools/buildman/func_test.py

@@ -219,12 +219,21 @@ class TestFunctional(unittest.TestCase):
         return command.RunPipe([[self._buildman_pathname] + list(args)],
                 capture=True, capture_stderr=True)
 
-    def _RunControl(self, *args, clean_dir=False, boards=None):
+        """Run buildman
+
+        Args:
+            args: List of arguments to pass
+            boards:
+            clean_dir: Used for tests only, indicates that the existing output_dir
+                should be removed before starting the build
+
+        Returns:
+            result code from buildman
+        """
         sys.argv = [sys.argv[0]] + list(args)
         options, args = cmdline.ParseArgs()
         result = control.DoBuildman(options, args, toolchains=self._toolchains,
                 make_func=self._HandleMake, boards=boards or self._boards,
-                clean_dir=clean_dir)
         self._builder = control.builder
         return result