Update query operation enum and add EXECUTE

Changed the query operation enum to contain implicit enum values instead
of providing. The operation was never used as a bitmask so it is pointless
to declare them as such.

Added the EXECUTE type to the enum and used it in qc_sqlite and
qc_mysqlembedded.

include/maxscale/query_classifier.h

@@ -82,19 +82,20 @@ typedef enum qc_query_type
  */
 typedef enum qc_query_op
 {
-    QUERY_OP_UNDEFINED     = 0,
-    QUERY_OP_SELECT        = (1 << 0),
-    QUERY_OP_UPDATE        = (1 << 1),
-    QUERY_OP_INSERT        = (1 << 2),
-    QUERY_OP_DELETE        = (1 << 3),
-    QUERY_OP_TRUNCATE      = (1 << 4),
-    QUERY_OP_ALTER         = (1 << 5),
-    QUERY_OP_CREATE        = (1 << 6),
-    QUERY_OP_DROP          = (1 << 7),
-    QUERY_OP_CHANGE_DB     = (1 << 8),
-    QUERY_OP_LOAD          = (1 << 9),
-    QUERY_OP_GRANT         = (1 << 10),
-    QUERY_OP_REVOKE        = (1 << 11)
+    QUERY_OP_UNDEFINED = 0,
+    QUERY_OP_SELECT,
+    QUERY_OP_UPDATE,
+    QUERY_OP_INSERT,
+    QUERY_OP_DELETE,
+    QUERY_OP_TRUNCATE,
+    QUERY_OP_ALTER,
+    QUERY_OP_CREATE,
+    QUERY_OP_DROP,
+    QUERY_OP_CHANGE_DB,
+    QUERY_OP_LOAD,
+    QUERY_OP_GRANT,
+    QUERY_OP_REVOKE,
+    QUERY_OP_EXECUTE,
 } qc_query_op_t;
 
 /**