configure: repeat ourselves for the benefit of CI

Our CI system echos the lines it executes but not the expansions. For
the sake of a line of extra verbosity during the configure phase lets
echo the invocation of script to stdout as well as the log when on CI.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221221090411.1995037-4-alex.bennee@linaro.org>

configure

@@ -83,9 +83,10 @@ rm -f config.log
 # Print a helpful header at the top of config.log
 echo "# QEMU configure log $(date)" >> config.log
 printf "# Configured with:" >> config.log
-printf " '%s'" "$0" "$@" >> config.log
-echo >> config.log
-echo "#" >> config.log
+# repeat the invocation to log and stdout for CI
+invoke=$(printf " '%s'" "$0" "$@")
+test -n "$GITLAB_CI" && echo "configuring with: $invoke"
+{ echo "$invoke"; echo; echo "#"; } >> config.log
 
 quote_sh() {
     printf "%s" "$1" | sed "s,','\\\\'',g; s,.*,'&',"