buildman: Change the exit codes

The current exit codes of 128 and 129 are useful in that they do not
conflict with those returned by tools, but they are not actually valid.
It seems better to pick some codes which work with 'bit bisect run'.

Update them to 100 (for errors) and 101 (for warnings).

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

tools/buildman/README

@@ -1114,15 +1114,15 @@ with -E, e.g. the migration warnings:
 When doing builds, Buildman's return code will reflect the overall result:
 
     0 (success)     No errors or warnings found
-    128             Errors found
-    129             Warnings found (only if no -W)
+    100             Errors found
+    101             Warnings found (only if no -W)
 
-You can use -W to tell Buildman to return 0 (success) instead of 129 when
+You can use -W to tell Buildman to return 0 (success) instead of 101 when
 warnings are found. Note that it can be useful to combine -E and -W. This means
-that all compiler warnings will produce failures (code 128) and all other
-warnings will produce success (since 129 is changed to 0).
+that all compiler warnings will produce failures (code 100) and all other
+warnings will produce success (since 101 is changed to 0).
 
-If there are both warnings and errors, errors win, so buildman returns 128.
+If there are both warnings and errors, errors win, so buildman returns 100.
 
 The -y option is provided (for use with -s) to ignore the bountiful device-tree
 warnings. Similarly, -Y tells buildman to ignore the migration warnings.

tools/buildman/control.py

@@ -361,7 +361,7 @@ def DoBuildman(options, args, toolchains=None, make_func=None, boards=None,
             fail, warned = builder.BuildBoards(commits, board_selected,
                                 options.keep_outputs, options.verbose)
             if fail:
-                return 128
+                return 100
             elif warned and not options.ignore_warnings:
-                return 129
+                return 101
     return 0

tools/buildman/func_test.py

@@ -454,7 +454,7 @@ class TestFunctional(unittest.TestCase):
         # Only sandbox should succeed, the others don't have toolchains
         self.assertEqual(self._builder.fail,
                          self._total_builds - self._commits)
-        self.assertEqual(ret_code, 128)
+        self.assertEqual(ret_code, 100)
 
         for commit in range(self._commits):
             for board in self._boards.GetList():