Restore alphabetical order of the system variables.

sql/set_var.cc:
  Restore alphabetical order of the system variables.
    - moved the have_merge_engine variable.

sql/set_var.cc

@@ -738,8 +738,8 @@ struct show_var_st init_vars[]= {
   {"have_geometry",           (char*) &have_geometry,               SHOW_HAVE},
   {"have_innodb",	      (char*) &have_innodb,		    SHOW_HAVE},
   {"have_isam",		      (char*) &have_isam,		    SHOW_HAVE},
-  {"have_ndbcluster",         (char*) &have_ndbcluster,             SHOW_HAVE},
   {"have_merge_engine",       (char*) &have_merge_db,               SHOW_HAVE},
+  {"have_ndbcluster",         (char*) &have_ndbcluster,             SHOW_HAVE},
   {"have_openssl",	      (char*) &have_openssl,		    SHOW_HAVE},
   {"have_query_cache",        (char*) &have_query_cache,            SHOW_HAVE},
   {"have_raid",		      (char*) &have_raid,		    SHOW_HAVE},