Fix build failure

mxs::rtrim was renamed to mxb::rtrim.

server/modules/routing/avrorouter/avro_client.cc

@@ -31,6 +31,7 @@
 #include <maxscale/dcb.hh>
 #include <maxscale/version.h>
 #include <maxbase/alloc.h>
+#include <maxbase/string.hh>
 #include <maxscale/buffer.hh>
 #include <maxscale/utils.hh>
 #include <maxscale/routingworker.hh>
@@ -585,7 +586,7 @@ GWBUF* read_avro_json_schema(std::string avrofile, std::string dir)
         std::stringstream ss;
         ss << file.rdbuf();
         std::string text = ss.str();
-        mxs::rtrim(text);
+        mxb::rtrim(text);
         text += '\n';
         mxs::Buffer buffer(std::vector<uint8_t>(text.begin(), text.end()));
         rval = buffer.release();