Bug#25302 (893 reduce/reduce conflicts in parser grammar)

This fix corrects build issues introduced by WL#3031:

- In the SQL grammar, 'USER' is a SQL 2003 reserved keyword,
and therefore should not be part of the keyword production.

- In sql/sql_parse.cc, the code for CREATE SERVER and ALTER SERVER
was not using proper format strings in the DBUG_PRINT statements.

sql/sql_parse.cc

@@ -5195,7 +5195,7 @@ create_sp_error:
     DBUG_PRINT("info", ("case SQLCOM_CREATE_SERVER"));
     if ((error= create_server(thd, &lex->server_options)))
     {
-      DBUG_PRINT("info", ("problem creating server",
+      DBUG_PRINT("info", ("problem creating server <%s>",
                           lex->server_options.server_name));
       my_error(error, MYF(0), lex->server_options.server_name);
       break;
@@ -5210,7 +5210,7 @@ create_sp_error:
     DBUG_PRINT("info", ("case SQLCOM_ALTER_SERVER"));
     if ((error= alter_server(thd, &lex->server_options)))
     {
-      DBUG_PRINT("info", ("problem altering server",
+      DBUG_PRINT("info", ("problem altering server <%s>",
                           lex->server_options.server_name));
       my_error(error, MYF(0), lex->server_options.server_name);
       break;

sql/sql_yacc.yy

@@ -9589,7 +9589,6 @@ keyword:
 	| TRUNCATE_SYM		{}
 	| UNICODE_SYM		{}
         | UNINSTALL_SYM         {}
-        | USER                  {}
 	| WRAPPER_SYM		{}
         | XA_SYM                {}
         | UPGRADE_SYM           {}