fvp-dockerfiles: Add debug version of stdout-flush-wrapper.sh

We still get occasional issues with LAVA failing to read FVP stdout
completely prior to detecting process termination. Have a version with
"set -x" and with longer pause to help debug those.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Idbe38d9d992320318cf69901221bc3a5cc7da805
diff --git a/dockerfile-template b/dockerfile-template
index 4f5fbbd..505a7b8 100644
--- a/dockerfile-template
+++ b/dockerfile-template
@@ -26,6 +26,7 @@
 
 COPY setup-sshd /usr/sbin/setup-sshd
 COPY stdout-flush-wrapper.sh /usr/bin/stdout-flush-wrapper.sh
+COPY stdout-flush-wrapper-debug.sh /usr/bin/stdout-flush-wrapper-debug.sh
 
 # Add the FVP model tarball
 # NOTE: some tarballs contain an installer script others don't, so it may be the case