Bump third-party/libswiftnav from bfa686b to 87b9931

dependabot[bot] · web-flow · commit def0aa781457 · 2020-11-24T13:05:40.000Z
Bumps [third-party/libswiftnav](https://github.com/swift-nav/libswiftnav) from `bfa686b` to `87b9931`. - [Release notes](https://github.com/swift-nav/libswiftnav/releases) - [Commits](swift-nav/libswiftnav@bfa686b...87b9931) Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/third-party/libswiftnav b/third-party/libswiftnav
@@ -1 +1 @@
-Subproject commit bfa686bac73d26118325697b1b8b79c9a2b3ed3b
+Subproject commit 87b99319af01ef582e8c30722072c6171b9a19cf
