Format readwritesplit with Astyle

Formatted readwritesplit with Astyle. Changed the initialization of
Backend::m_modutil_state to use curly braces to cope with Astyle's lack of
support for curly braces inside parentheses.

server/modules/routing/readwritesplit/rwbackend.cc

@@ -10,7 +10,7 @@ namespace maxscale
 RWBackend::RWBackend(SERVER_REF* ref):
     mxs::Backend(ref),
     m_reply_state(REPLY_STATE_DONE),
-    m_modutil_state({}),
+    m_modutil_state{0},
     m_command(0),
     m_opening_cursor(false),
     m_expected_rows(0),