Fix PRESUBMIT.py so it is python3-compatible.

Change-Id: I751220a9bfbfff61c281c6592477e11ab60877fb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/101700
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
diff --git a/runtime/PRESUBMIT.py b/runtime/PRESUBMIT.py
index 44c53df..e790a8b 100644
--- a/runtime/PRESUBMIT.py
+++ b/runtime/PRESUBMIT.py
@@ -21,7 +21,7 @@
   match = re.search('\\bmemcpy\\b', content)
   if match:
     line_number = content[0:match.start()].count('\n') + 1
-    print "%s:%d: use of memcpy is forbidden" % (filename, line_number)
+    print("%s:%d: use of memcpy is forbidden" % (filename, line_number))
     return 1
   return 0