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>

tools/buildman/builderthread.py

@@ -197,7 +197,8 @@ class BuilderThread(threading.Thread):
                         src_dir = os.getcwd()
                     else:
                         args.append('O=build')
-                args.append('-s')
+                if not self.builder.verbose_build:
+                    args.append('-s')
                 if self.builder.num_jobs is not None:
                     args.extend(['-j', str(self.builder.num_jobs)])
                 config_args = ['%s_defconfig' % brd.target]