Add OpenBSD support
diff --git a/grpc.gemspec b/grpc.gemspec
index ce23e6f..6b35d7a 100644
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -1125,6 +1125,7 @@
   s.files += %w( third_party/cares/ares_build.h )
   s.files += %w( third_party/cares/config_linux/ares_config.h )
   s.files += %w( third_party/cares/config_darwin/ares_config.h )
+  s.files += %w( third_party/cares/config_openbsd/ares_config.h )
   s.files += %w( third_party/cares/cares/ares__close_sockets.c )
   s.files += %w( third_party/cares/cares/ares__get_hostent.c )
   s.files += %w( third_party/cares/cares/ares__read_line.c )