arc lint: ignore /tests/ in chmod

shell scripts in scripts don't need
to be chmod +x to work. In fact most are not.
Of the tests I found from a simple search:
65 are chmod +x
84 are chmod -x

simply disable the check for test shell scripts.

Recommit requested by:	cem, rgrimes

.arclint

@@ -9,7 +9,8 @@
       "type": "spelling"
     },
     "chmod": {
-      "type": "chmod"
+      "type": "chmod",
+      "exclude": "(/tests/)"
     },
     "merge-conflict": {
       "type": "merge-conflict"