stop gcc complaints about func ptr conversions
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index 0f05347..679ca43 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -665,16 +665,16 @@
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE grpcsharp_call_recv_initial_metadata(
-	grpc_call *call, grpcsharp_batch_context *ctx) {
-	/* TODO: don't use magic number */
-	grpc_op ops[1];
-	ops[0].op = GRPC_OP_RECV_INITIAL_METADATA;
-	ops[0].data.recv_initial_metadata = &(ctx->recv_initial_metadata);
-	ops[0].flags = 0;
-	ops[0].reserved = NULL;
+  grpc_call *call, grpcsharp_batch_context *ctx) {
+  /* TODO: don't use magic number */
+  grpc_op ops[1];
+  ops[0].op = GRPC_OP_RECV_INITIAL_METADATA;
+  ops[0].data.recv_initial_metadata = &(ctx->recv_initial_metadata);
+  ops[0].flags = 0;
+  ops[0].reserved = NULL;
 
-	return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
-		NULL);
+  return grpc_call_start_batch(call, ops, sizeof(ops) / sizeof(ops[0]), ctx,
+    NULL);
 }
 
 GPR_EXPORT grpc_call_error GPR_CALLTYPE
@@ -898,41 +898,43 @@
 }
 
 GPR_EXPORT grpc_credentials *GPR_CALLTYPE grpcsharp_composite_credentials_create(
-	grpc_credentials *creds1,
-	grpc_credentials *creds2) {
-	return grpc_composite_credentials_create(creds1, creds2, NULL);
+  grpc_credentials *creds1,
+  grpc_credentials *creds2) {
+  return grpc_composite_credentials_create(creds1, creds2, NULL);
 }
 
 /* Metadata credentials plugin */
 
 GPR_EXPORT void GPR_CALLTYPE grpcsharp_metadata_credentials_notify_from_plugin(
-	void *callback_ptr, void *user_data, grpc_metadata_array *metadata,
-	grpc_status_code status, const char *error_details) {
-	grpc_credentials_plugin_metadata_cb cb = (grpc_credentials_plugin_metadata_cb)callback_ptr;
-	cb(user_data, metadata->metadata, metadata->count, status, error_details);
+    grpc_credentials_plugin_metadata_cb cb,
+    void *user_data, grpc_metadata_array *metadata,
+  grpc_status_code status, const char *error_details) {
+  cb(user_data, metadata->metadata, metadata->count, status, error_details);
 }
 
 typedef void(GPR_CALLTYPE *grpcsharp_metadata_interceptor_func)(
-	void *state, const char *service_url, void *callback_ptr,
-	void *user_data, gpr_int32 is_destroy);
+  void *state, const char *service_url, grpc_credentials_plugin_metadata_cb cb,
+  void *user_data, gpr_int32 is_destroy);
 
 static void grpcsharp_get_metadata_handler(void *state, const char *service_url,
-	grpc_credentials_plugin_metadata_cb cb, void *user_data) {
-	grpcsharp_metadata_interceptor_func interceptor = (grpcsharp_metadata_interceptor_func)state;
-	interceptor(state, service_url, (void*)cb, user_data, 0);
+  grpc_credentials_plugin_metadata_cb cb, void *user_data) {
+  grpcsharp_metadata_interceptor_func interceptor =
+      (grpcsharp_metadata_interceptor_func)(gpr_intptr)state;
+  interceptor(state, service_url, cb, user_data, 0);
 }
 
 static void grpcsharp_metadata_credentials_destroy_handler(void *state) {
-	grpcsharp_metadata_interceptor_func interceptor = (grpcsharp_metadata_interceptor_func)state;
-	interceptor(state, NULL, NULL, NULL, 1);
+  grpcsharp_metadata_interceptor_func interceptor =
+      (grpcsharp_metadata_interceptor_func)(gpr_intptr)state;
+  interceptor(state, NULL, NULL, NULL, 1);
 }
 
 GPR_EXPORT grpc_credentials *GPR_CALLTYPE grpcsharp_metadata_credentials_create_from_plugin(
-	grpcsharp_metadata_interceptor_func metadata_interceptor) {
+  grpcsharp_metadata_interceptor_func metadata_interceptor) {
   grpc_metadata_credentials_plugin plugin;
   plugin.get_metadata = grpcsharp_get_metadata_handler;
   plugin.destroy = grpcsharp_metadata_credentials_destroy_handler;
-  plugin.state = metadata_interceptor;
+  plugin.state = (void*)(gpr_intptr)metadata_interceptor;
   return grpc_metadata_credentials_create_from_plugin(plugin, NULL);
 }