GHOST: add back-trace handler to the API

Add a back-trace handler to GHOST, so error handlers can include a
back-trace (when supported).

No functional changes.

source/blender/windowmanager/intern/wm_playanim.c

@@ -33,6 +33,7 @@
 #include "BLI_path_util.h"
 #include "BLI_rect.h"
 #include "BLI_string.h"
+#include "BLI_system.h"
 #include "BLI_utildefines.h"
 
 #include "IMB_colormanagement.h"
@@ -1536,6 +1537,8 @@ static char *wm_main_playanim_intern(int argc, const char **argv)
 
     GHOST_EventConsumerHandle consumer = GHOST_CreateEventConsumer(ghost_event_proc, &ps);
 
+    GHOST_SetBacktraceHandler((GHOST_TBacktraceFn)BLI_system_backtrace);
+
     g_WS.ghost_system = GHOST_CreateSystem();
     GHOST_AddEventConsumer(g_WS.ghost_system, consumer);
 

source/blender/windowmanager/intern/wm_window.c

@@ -23,6 +23,7 @@
 
 #include "BLI_blenlib.h"
 #include "BLI_math.h"
+#include "BLI_system.h"
 #include "BLI_utildefines.h"
 
 #include "BLT_translation.h"
@@ -1543,6 +1544,8 @@ void wm_ghost_init(bContext *C)
       consumer = GHOST_CreateEventConsumer(ghost_event_proc, C);
     }
 
+    GHOST_SetBacktraceHandler((GHOST_TBacktraceFn)BLI_system_backtrace);
+
     g_system = GHOST_CreateSystem();
 
     GHOST_Debug debug = {0};