Support Unknown System build with BACKWARD_SYSTEM_UNKNOWN in user take stack trace case.

Ghost-LZW · Ghost-LZW · commit bbe537f408f4 · 2022-12-30T19:39:22.000+08:00
diff --git a/backward.hpp b/backward.hpp
@@ -727,6 +727,7 @@ template <typename TAG> class StackTraceImpl {
   }
   size_t thread_id() const { return 0; }
   void skip_n_firsts(size_t) {}
+  void *const *begin() const { return nullptr; }
 };
 
 class StackTraceImplBase {

Original file line number	Diff line number	Diff line change
`@@ -727,6 +727,7 @@ template <typename TAG> class StackTraceImpl {`
`727`	`727`	`}`
`728`	`728`	`size_t thread_id() const { return 0; }`
`729`	`729`	`void skip_n_firsts(size_t) {}`
	`730`	`+ void const begin() const { return nullptr; }`
`730`	`731`	`};`
`731`	`732`
`732`	`733`	`class StackTraceImplBase {`