buildman: Show 'make' command line when -V is used

When a verbose build it selected, show the make command before the output of
that command.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/builder.py b/tools/buildman/builder.py
index 54f3292..72353b9 100644
--- a/tools/buildman/builder.py
+++ b/tools/buildman/builder.py
@@ -335,6 +335,9 @@
         cmd = [self.gnu_make] + list(args)
         result = command.RunPipe([cmd], capture=True, capture_stderr=True,
                 cwd=cwd, raise_on_error=False, **kwargs)
+        if self.verbose_build:
+            result.stdout = '%s\n' % (' '.join(cmd)) + result.stdout
+            result.combined = '%s\n' % (' '.join(cmd)) + result.combined
         return result
 
     def ProcessResult(self, result):