Removing unused variable (old have_isam).

sql/mysql_priv.h:
  Removing isam option
sql/mysqld.cc:
  Removing isam option
sql/set_var.cc:
  Removing isam option.

sql/mysql_priv.h

@@ -1431,7 +1431,6 @@ extern handlerton myisam_hton;
 extern handlerton myisammrg_hton;
 extern handlerton heap_hton;
 
-extern SHOW_COMP_OPTION have_isam;
 extern SHOW_COMP_OPTION have_row_based_replication;
 extern SHOW_COMP_OPTION have_raid, have_openssl, have_symlink;
 extern SHOW_COMP_OPTION have_query_cache;

sql/mysqld.cc

@@ -8150,7 +8150,6 @@ static void create_pid_file()
 /*****************************************************************************
   Instantiate have_xyx for missing storage engines
 *****************************************************************************/
-#undef have_isam
 #undef have_berkeley_db
 #undef have_innodb
 #undef have_ndbcluster
@@ -8163,7 +8162,6 @@ static void create_pid_file()
 
 SHOW_COMP_OPTION have_berkeley_db= SHOW_OPTION_NO;
 SHOW_COMP_OPTION have_innodb= SHOW_OPTION_NO;
-SHOW_COMP_OPTION have_isam= SHOW_OPTION_NO;
 SHOW_COMP_OPTION have_ndbcluster= SHOW_OPTION_NO;
 SHOW_COMP_OPTION have_example_db= SHOW_OPTION_NO;
 SHOW_COMP_OPTION have_archive_db= SHOW_OPTION_NO;

sql/set_var.cc

@@ -629,7 +629,6 @@ sys_var_have_variable sys_have_federated_db("have_federated_engine",
                                             &have_federated_db);
 sys_var_have_variable sys_have_geometry("have_geometry", &have_geometry);
 sys_var_have_variable sys_have_innodb("have_innodb", &have_innodb);
-sys_var_have_variable sys_have_isam("have_isam", &have_isam);
 sys_var_have_variable sys_have_ndbcluster("have_ndbcluster", &have_ndbcluster);
 sys_var_have_variable sys_have_openssl("have_openssl", &have_openssl);
 sys_var_have_variable sys_have_partition_db("have_partitioning",
@@ -749,7 +748,6 @@ SHOW_VAR init_vars[]= {
   {sys_have_federated_db.name,(char*) &have_federated_db,           SHOW_HAVE},
   {sys_have_geometry.name,    (char*) &have_geometry,               SHOW_HAVE},
   {sys_have_innodb.name,      (char*) &have_innodb,                 SHOW_HAVE},
-  {sys_have_isam.name,        (char*) &have_isam,                   SHOW_HAVE},
   {sys_have_ndbcluster.name,  (char*) &have_ndbcluster,             SHOW_HAVE},
   {sys_have_openssl.name,     (char*) &have_openssl,                SHOW_HAVE},
   {sys_have_partition_db.name,(char*) &have_partition_db,           SHOW_HAVE},