Remove another bashism from run_tests.sh

Current we check for various error codes with [ $x == "NN" ].  However
'==' is not actually a correct operator for the [ (test) command.  It
should be either '=' for string comparison or '-eq' for integer
comparison.  It appears that the bash builtin version of test
implements '==' though, so we were getting away with it, as long as
/bin/sh was bash - or the testsuite generated no errors.

This patch fixes the usage of test so that it should work on non-bash
shells.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 4cec62c..c2c39b6 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -24,11 +24,11 @@
 	tot_pass=$((tot_pass + 1))
     else
 	ret="$?"
-	if [ "$ret" == "1" ]; then
+	if [ "$ret" -eq 1 ]; then
 	    tot_config=$((tot_config + 1))
-	elif [ "$ret" == "2" ]; then
+	elif [ "$ret" -eq 2 ]; then
 	    tot_fail=$((tot_fail + 1))
-	elif [ "$ret" == "$VGCODE" ]; then
+	elif [ "$ret" -eq $VGCODE ]; then
 	    tot_vg=$((tot_vg + 1))
 	else
 	    tot_strange=$((tot_strange + 1))