Tell mypy to ignore import of cython module

Mypy complains following the import of cPerf because it cannot find the
module. This is because it is a cython module which mypy cannot inspect.
This commit tells mypy to ignore that import.

Reviewed By: danilaml

Differential Revision: https://reviews.llvm.org/D95065

Author: Thomas Preud'homme

lnt/testing/profile/perf.py

@@ -7,7 +7,7 @@
 import traceback
 
 try:
-    from . import cPerf
+    from . import cPerf  # type: ignore  # mypy cannot process Cython modules
 except Exception:
     pass