Fix crash on QNX

src/aarch64/Gis_signal_frame.c

@@ -73,6 +73,8 @@ unw_is_signal_frame (unw_cursor_t *cursor)
   arg = c->dwarf.as_arg;
 
   ip = c->dwarf.ip;
+  if (unlikely(!ip))
+    return 0;
 
   ret = (*a->access_mem) (as, ip, &w0, 0, arg);
   if (ret < 0)

src/arm/Gtrace.c

@@ -251,6 +251,12 @@ trace_init_addr (unw_tdep_frame_t *f,
       && likely(dwarf_put (d, d->loc[UNW_ARM_R15], pc) >= 0)
       && likely((ret = unw_step (cursor)) >= 0))
     *f = c->frame_info;
+  #if defined (__QNX__)
+    if (unw_is_signal_frame (cursor))
+      {
+        return NULL;
+      }
+  #endif
 
   /* If unw_step() stopped voluntarily, remember that, even if it
      otherwise could not determine anything useful.  This avoids