Disable art_verifier on mac.

Test: no
Change-Id: I802292b83456ccf0e940863105de648c8ea498a9
diff --git a/tools/art_verifier/Android.bp b/tools/art_verifier/Android.bp
index af9744f..afd52fb 100644
--- a/tools/art_verifier/Android.bp
+++ b/tools/art_verifier/Android.bp
@@ -36,6 +36,9 @@
                 "libtombstoned_client_static",
             ],
         },
+        darwin: {
+            enabled: false,
+        },
     },
 }