Update arrayfire submodule to v3.7.2 tag

9prady9 · 9prady9 · commit 832eeb0f0414 · 2020-07-20T00:24:45.000+05:30
diff --git a/arrayfire b/arrayfire
@@ -1 +1 @@
-Subproject commit fbea2aeb6f7f2d277dcb0ab425a77bb18ed22291
+Subproject commit 218dd2c99300e77496239ade76e94b0def65d032
