Separate the posix part of the c-ares driver
diff --git a/BUILD b/BUILD
index 3df4be8..44b8777 100644
--- a/BUILD
+++ b/BUILD
@@ -1333,6 +1333,7 @@
name = "grpc_resolver_dns_ares",
srcs = [
"src/core/ext/filters/client_channel/resolver/dns/c_ares/dns_resolver_ares.cc",
+ "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc",
"src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc",
"src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc",
"src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_fallback.cc",