use POSIX equality test in check-lxdialog.sh

The "==" operator is not in POSIX, so use -eq instead.

---
index cdca738..9681476 100644

@@ -51,7 +51,7 @@ usage() {
 	printf "Usage: $0 [-check compiler options|-header|-library]\n"
 }
 
-if [ $# == 0 ]; then
+if [ $# -eq 0 ]; then
 	usage
 	exit 1
 fi

Apart from that, == is for strings, -eq is for numbers, so that wrong variable content can be caught ("$x" -eq 123 where x=123foo throws an error).

So yes, the patch is good.

Jan