Bump third_party/gflags from `addd749` to `827c769`

Bumps [third_party/gflags](https://github.com/gflags/gflags) from `addd749` to `827c769`.
- [Release notes](https://github.com/gflags/gflags/releases)
- [Commits](https://github.com/gflags/gflags/compare/addd749114fab4f24b7ea1e0f2f837584389e52c...827c769e5fc98e0f2a34c47cef953cc6328abced)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

third_party/gflags

diff --git a/third_party/gflags b/third_party/gflags
index addd749..827c769 160000
--- a/third_party/gflags
+++ b/third_party/gflags
@@ -1 +1 @@
-Subproject commit addd749114fab4f24b7ea1e0f2f837584389e52c
+Subproject commit 827c769e5fc98e0f2a34c47cef953cc6328abced