[PATCH 3/5] buildman: Make sure that -o is given with -w

[sjg at google.com]

It is a bad idea to use the default output directory ('..') with -w since
it does a build in that directory and writes various files these.

Require that -o is given to avoid this problem.

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

 tools/buildman/README       | 3 ++-
 tools/buildman/cmdline.py   | 3 +--
 tools/buildman/control.py   | 4 ++++
 tools/buildman/func_test.py | 6 ++++++
 4 files changed, 13 insertions(+), 3 deletions(-)

Applied to u-boot-dm, thanks!