rpc: fix swapserverrpc build

Author: bhandras

swapserverrpc/gen_protos.sh

@@ -9,6 +9,7 @@ function generate() {
   do
     protoc -I/usr/local/include -I. -I.. \
       --go_out . --go_opt paths=source_relative \
+      --go-grpc_out . --go-grpc_opt paths=source_relative \
       "${file}"
   done
 }