buildman: Add an option to write the full build output

Normally buildman runs with 'make -s' meaning that only errors and warnings
appear in the log file. Add a -V option to run make in verbose mode, and
with V=1, causing a full build log to be created.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/cmdline.py b/tools/buildman/cmdline.py
index e884e19..e8a6dad 100644
--- a/tools/buildman/cmdline.py
+++ b/tools/buildman/cmdline.py
@@ -82,6 +82,8 @@
           default=False, help='Show boards with unknown build result')
     parser.add_option('-v', '--verbose', action='store_true',
           default=False, help='Show build results while the build progresses')
+    parser.add_option('-V', '--verbose-build', action='store_true',
+          default=False, help='Run make with V=1, showing all output')
     parser.add_option('-x', '--exclude', dest='exclude',
           type='string', action='append',
           help='Specify a list of boards to exclude, separated by comma')