Merge pull request #2861 from gatecat/fix-def-fill

def2stream: Don't clear DEF fill created by newer klayout

Author: maliberty

flow/util/def2stream.py

@@ -31,7 +31,7 @@
 print("[INFO] Clearing cells...")
 for i in main_layout.each_cell():
     if i.cell_index() != top_cell_index:
-        if not i.name.startswith("VIA_"):
+        if not i.name.startswith("VIA_") and not i.name.endswith("_DEF_FILL"):
             i.clear()
 
 # Load in the gds to merge