Revert "Merge pull request #16158 from apolcyn/revert_windows_breakage"

This reverts commit d9e8f86675cf923714b3ead4b06087e14a88c08c, reversing
changes made to 04847aeb1e62bc528d88fa3c47daa24a4cf629b3.
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index 23edaec..5c3649a 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -802,8 +802,11 @@
                       '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_ev_driver_windows.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',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_posix.cc',
+                      'src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper_windows.cc',
                       'src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.cc',
                       'src/core/ext/filters/client_channel/resolver/sockaddr/sockaddr_resolver.cc',
                       'src/cpp/ext/filters/census/grpc_context.cc',