buildman: Don't default to -e when using -s

When using summary mode (-s) we don't always want to display errors.
Allow this option to be omitted.

Series-to: u-boot
Series-cc: albert
Change-Id: I6b37754d55eb920ecae114fceba55834b43ea3b9
Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Albert Aribaud <albert.u.boot@aribaud.net>

tools/buildman/control.py

@@ -188,7 +188,8 @@ def DoBuildman(options, args, toolchains=None, make_func=None, boards=None,
     else:
         series = None
         options.verbose = True
-        options.show_errors = True
+        if not options.summary:
+            options.show_errors = True
 
     # By default we have one thread per CPU. But if there are not enough jobs
     # we can have fewer threads and use a high '-j' value for make.