[GWP-ASan] Silence gcc error

Summary: It complains about reaching the end of a non-void returning function.

Reviewers: eugenis, hctim, morehouse

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D74578

GitOrigin-RevId: ef7488ef205ceb018af463b82386f5ee6a365445
Change-Id: I1cea8990d47626141d66c8972529490937736a71
diff --git a/gwp_asan/platform_specific/utilities_posix.cpp b/gwp_asan/platform_specific/utilities_posix.cpp
index 45b1939..0e60598 100644
--- a/gwp_asan/platform_specific/utilities_posix.cpp
+++ b/gwp_asan/platform_specific/utilities_posix.cpp
@@ -84,6 +84,7 @@
   case AlignmentStrategy::DEFAULT:
     __builtin_unreachable();
   }
+  __builtin_unreachable();
 }
 
 } // namespace gwp_asan