"git update --init" in the install script

Former-commit-id: 49e723a

Author: slembcke

install.sh

@@ -269,7 +269,7 @@ if $INSTALL ; then
 
 	if [[ -d "$SCRIPT_DIR/.git" ]]; then
 		# If this is a git repo, make sure that the Chipmunk submodule is checked out and current.
-		git submodule update 1>>"${ERROR_LOG}" 2>>"${ERROR_LOG}"
+		git submodule update --init 1>>"${ERROR_LOG}" 2>>"${ERROR_LOG}"
 		check_status
 	elif [[ ! -d "$SCRIPT_DIR/external/Chipmunk" ]]; then
 		# Not a git repo, download Chipmunk files.