[gimp] tools: in performance-log-expand.py, preserve threads with empty stacks

[Ell <ell src gnome org>]

commit fb95d3b86ee78e6b409a33a7aa3241690e3e0249
Author: Ell <ell_se yahoo com>
Date:   Wed Nov 7 13:57:56 2018 -0500

    tools: in performance-log-expand.py, preserve threads with empty stacks
    
    ... which can be present in logs since last commit.

 tools/performance-log-expand.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/tools/performance-log-expand.py b/tools/performance-log-expand.py
index 36fc1b6c8e..bc04d83a53 100755
--- a/tools/performance-log-expand.py
+++ b/tools/performance-log-expand.py
@@ -84,7 +84,7 @@ for sample in (log.find ("samples") or empty_element).iterfind ("sample"):
             last_thread[0] = attrib
             last_thread[1] = frames
 
-            if not frames:
+            if not frames and thread.text is None:
                 del last_backtrace[id]
 
         for thread in list (backtrace):