configure: Quote the configure args printed in config.log

Use the same mechanism we use for printing the configure command
line to config-host.mak to print it to config.log. This fixes a
bug where the config.log version didn't quote arguments with spaces.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

configure

@@ -22,7 +22,9 @@ rm -f config.log
 
 # Print a helpful header at the top of config.log
 echo "# QEMU configure log $(date)" >> config.log
-echo "# produced by $0 $*" >> config.log
+printf "# Configured with:" >> config.log
+printf " '%s'" "$0" "$@" >> config.log
+echo >> config.log
 echo "#" >> config.log
 
 compile_object() {