scripts: fixed broken Lua with non-GNU sed

scripts/embed-lua.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
 set -e
 # clean unnecessary stuff from the lua file
-alias strip="sed -e 's/^[\t ]*//g; s/  */ /g; /^--/d; /^$/d'"
+alias strip="sed -e 's/^[\t ]+//g; s/  */ /g; /^--/d; /^$/d'"
 if command -v xxd > /dev/null 2>&1; then
 	strip < "$1" | xxd -i -
 else