Update libswiftnav SHA1 to match master head

Adel Mamin · Adel Mamin · commit 36c39fff1d42 · 2016-08-12T16:19:31.000+03:00
diff --git a/libswiftnav b/libswiftnav
@@ -1 +1 @@
-Subproject commit 18c8d96249d44a2330d35983bc1ed51ec7ed0c35
+Subproject commit da4bfcb7db04021a730e9bd6b1b0781dfd69abc0
