MXS-1275: SetSqlModeParser moved under MySQLClient

That's where it belongs as it is only the mysql client protocol that
will use it. It's a bit unfortunate that the qc test program compare
now needs to include a file from a protocol module directory, but
the fact is that the query classifier implementation and the test
programs should actually be *under* the mysql client protocol module.

server/modules/protocol/MySQL/MySQLClient/CMakeLists.txt

@@ -2,3 +2,7 @@ add_library(MySQLClient SHARED mysql_client.cc)
 target_link_libraries(MySQLClient maxscale-common  MySQLCommon)
 set_target_properties(MySQLClient PROPERTIES VERSION "1.0.0")
 install_module(MySQLClient core)
+
+if(BUILD_TESTS)
+  add_subdirectory(test)
+endif()