[Windows] Enable crash reporter on MinGW builds, use libbacktrace to generate stack trace from DWARF symbols.

platform/windows/crash_handler_windows.h

@@ -35,12 +35,15 @@
 #include <windows.h>
 
 // Crash handler exception only enabled with MSVC
-#if defined(DEBUG_ENABLED) && defined(_MSC_VER)
+#if defined(DEBUG_ENABLED)
 #define CRASH_HANDLER_EXCEPTION 1
 
+#ifdef _MSC_VER
 extern DWORD CrashHandlerException(EXCEPTION_POINTERS *ep);
 #endif
 
+#endif
+
 class CrashHandler {
 	bool disabled;