Bug #28846 Use of undocumented Prepared Statements crashes server

- Manual merge patch.


sql/sql_yacc.yy:
  Corrected merge error. ALTER VIEW rules has been split in two and both
  rules need to be checked for SP-context.

sql/sql_yacc.yy

@@ -5187,6 +5187,12 @@ alter:
           */
           {
             LEX *lex= Lex;
+
+            if (lex->sphead)
+            {
+              my_error(ER_SP_BADSTATEMENT, MYF(0), "ALTER VIEW");
+              MYSQL_YYABORT;
+            }
             lex->create_view_algorithm= VIEW_ALGORITHM_UNDEFINED;
 	    lex->create_view_mode= VIEW_ALTER;
 	  }