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/dtoc/main.py b/tools/dtoc/main.py
index 6c91450..59b98b0 100755
--- a/tools/dtoc/main.py
+++ b/tools/dtoc/main.py
@@ -58,8 +58,9 @@
     test_dtoc.setup()
 
     result = test_util.run_test_suites(
-        toolname='dtoc', debug=True, verbosity=1, test_preserve_dirs=False,
-        processes=processes, test_name=test_name, toolpath=[],
+        toolname='dtoc', debug=True, verbosity=1, no_capture=False,
+        test_preserve_dirs=False, processes=processes, test_name=test_name,
+        toolpath=[],
         class_and_module_list=[test_dtoc.TestDtoc,test_src_scan.TestSrcScan])
 
     return (0 if result.wasSuccessful() else 1)