contrib/clang-format-ignorelist

--- a/contrib/clang-format-ignorelist	Tue Oct 15 09:52:33 2019 -0400
+++ b/contrib/clang-format-ignorelist	Tue Oct 15 09:54:05 2019 -0400
@@ -1,6 +1,5 @@
 # Files that just need to be migrated to the formatter.
 # Do not add new files here!
-mercurial/cext/dirs.c
 mercurial/cext/manifest.c
 mercurial/cext/osutil.c
 # Vendored code that we should never format: