buildman: Add a flag to force mrproper on failure

When a file is removed by a commit (e.g. include/common.h yay!) it can
cause incremental build failures since one of the dependency files from
a previous build may mention the file.

Add an option to run 'make mrproper' automatically when a build fails.
This can be used to automatically resolve the problem, without always
adding the large overhead of 'make mrproper' to every build.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/control.py b/tools/buildman/control.py
index 8f6850c..f2dd878 100644
--- a/tools/buildman/control.py
+++ b/tools/buildman/control.py
@@ -656,6 +656,7 @@
             no_subdirs=args.no_subdirs, full_path=args.full_path,
             verbose_build=args.verbose_build,
             mrproper=args.mrproper,
+            fallback_mrproper=args.fallback_mrproper,
             per_board_out_dir=args.per_board_out_dir,
             config_only=args.config_only,
             squash_config_y=not args.preserve_config_y,