Make query classifier self-contained.

Only the query classifier needs the functionality of the embedded
server, while the rest of MaxScale is content with the client
library or Connector/C.

This have now been rearranged so that query-classifier links with
the embedded static library and then explicitly exports its own
functions using the query_classifier.map linker script. That way
query classifier will use the embedded library, while the rest of
maxscale use the client library, and this without conflicts.

Currently, query_classifier is not linked to maxscale-common,
but executables must link to maxscale-common and query_classifier.

query_classifier/query_classifier.h

@@ -83,6 +83,12 @@ typedef enum
 
 #define QUERY_IS_TYPE(mask,type) ((mask & type) == type)
 
+bool qc_init(int argc, char** argv, char** groups);
+void qc_end();
+
+bool qc_thread_init();
+void qc_thread_end();
+
 /**
  * Create THD and use it for creating parse tree. Examine parse tree and
  * classify the query.