Bump third-party/libswiftnav from c79fc26 to 3ef6140

dependabot[bot] · web-flow · commit e7bb6da430f1 · 2021-02-26T13:05:00.000Z
Bumps [third-party/libswiftnav](https://github.com/swift-nav/libswiftnav) from `c79fc26` to `3ef6140`. - [Release notes](https://github.com/swift-nav/libswiftnav/releases) - [Commits](swift-nav/libswiftnav@c79fc26...3ef6140) Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/third-party/libswiftnav b/third-party/libswiftnav
@@ -1 +1 @@
-Subproject commit c79fc26e4df99300146a855714092b0ad8043e86
+Subproject commit 3ef6140f5e09e50e3292bc91a4511e33fefa5a6c
