tools: Plumb in capture control

Add control of capturing output into u_boot_pylib and the tools which
use it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/main.py b/tools/buildman/main.py
index 72571b2..77b9beb 100755
--- a/tools/buildman/main.py
+++ b/tools/buildman/main.py
@@ -49,7 +49,7 @@
     # Run the entry tests first ,since these need to be the first to import the
     # 'entry' module.
     result = test_util.run_test_suites(
-        'buildman', debug, verbose, False, args.threads, test_name, [],
+        'buildman', debug, verbose, False, False, args.threads, test_name, [],
         [test.TestBuild, func_test.TestFunctional, 'buildman.toolchain'])
 
     return (0 if result.wasSuccessful() else 1)