clone.sh: Run with shell tracing

Required to debug https://linaro.atlassian.net/browse/TFC-210, but as any
issue may appear at any time, it should always run like that.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I2a55f883d88f0043d78852d26c4c0d0fc6977eba
1 file changed