From: Xiangzhe <xiangzhedev@gmail.com>
Subject: [PATCH] build: make libunwind detection authoritative

UniversalStacktrace probes for libunwind headers independently of CMake.  If
CMake has deliberately disabled or failed to find libunwind, this compiles
calls to libunwind without linking it.  Pass the CMake result to the header so
libunwind can be controlled without automagic linkage.

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -134,0 +135,6 @@ find_package(Unwind)
+if(Unwind_FOUND)
+  add_compile_definitions(USE_UNWIND=1)
+else()
+  add_compile_definitions(USE_UNWIND=0)
+endif()
+
--- a/external_imported/UniversalStacktrace/ust/ust.hpp
+++ b/external_imported/UniversalStacktrace/ust/ust.hpp
@@ -9,0 +10 @@
+#ifndef USE_UNWIND
@@ -19,0 +21,6 @@
+#elif USE_UNWIND
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+#else
+#include <execinfo.h>
+#endif