[PATCH v2 24/28] buildman: Make -I the default

[sjg at google.com]

At present buildman defaults to running 'mrproper' on every thread before
it starts building commits for each board. This can add a delay of about 5
seconds to the start of the process, since the tools and other invariants
must be rebuilt.

In particular, a build without '-b', to build current source, runs much
slower without -I, since any existing build is removed, thus losing the
possibility of an incremental build.

Partly this behaviour was to avoid strange build-system problems caused by
running 'make defconfig' for one board and then one with a different
architecture. But these problems were fixed quite a while ago.

The -I option (which disabled mrproper) was introduced four years ago and
does not seem to cause any problems with builds.

So make -I the default and deprecate the option. To allow use of
'mrproper', add a new -m flag.

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

Changes in v2: None

 tools/buildman/README           | 13 ++++++-------
 tools/buildman/builder.py       |  7 +++----
 tools/buildman/builderthread.py |  6 +++---
 tools/buildman/cmdline.py       |  5 ++++-
 tools/buildman/control.py       |  6 +++++-
 tools/buildman/func_test.py     | 28 ++++++++++++++++++++--------
 6 files changed, 41 insertions(+), 24 deletions(-)

Applied to u-boot-dm, thanks!