Roll third_party/libunwind/src/ 278e5fbaf..2602aecdf (3 commits)

https://chromium.googlesource.com/external/github.com/llvm/llvm-project/libunwind.git/+log/278e5fbafc5b..2602aecdf4bf

Created with:
  roll-dep third_party/libunwind/src

Change-Id: I796258278e6172f40116ee178c084ce1ba3ada3d
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/115172
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Auto-Submit: Andy Phan <andyphan@chromium.org>
diff --git a/DEPS b/DEPS
index 1d4a9f2..34ab9c1 100644
--- a/DEPS
+++ b/DEPS
@@ -154,7 +154,7 @@
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling libunwind
   # and whatever else without interference from each other.
-  'libunwind_revision': '278e5fbafc5b1707a5c4d09c3fc351cd4aa1630a',
+  'libunwind_revision': '2602aecdf4bfa2a4bd70722937b2ec503d8c46c8',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling markupsafe
   # and whatever else without interference from each other.