Fix broken embedded build (broken by the patch for Bug#12713, first part).

client/mysqltest.c:
  Remove a call to my_message() (server call) in case of a client error.
  It asserts in the embedded build now, since is called after send_ok().
libmysqld/emb_qcache.cc:
  Use net_send_eof (embedded implementation) in embedded query cache/
  send result to client, since send_eof currently does not
  send anything.
libmysqld/emb_qcache.h:
  Declare net_send_eof.
libmysqld/lib_sql.cc:
  Fix the main loop of the embedded server to use the new Diagnostics_area
  API.
sql/log.cc:
  Silence errors of open_performance_schema_table. This function
  is called for general logging, and it happens after the error
  has been sent to the client, and thus triggers an assert.
storage/myisam/ha_myisam.cc:
  Remove an old hack that broke repair.test in embedded build:
  unless we clear an error here, the server attempts to send OK after
  ERROR. This currently asserts.

client/mysqltest.c

@@ -8018,7 +8018,6 @@ REPLACE *init_replace(char * *from, char * *to,uint count,
     if (!len)
     {
       errno=EINVAL;
-      my_message(0,"No to-string for last from-string",MYF(ME_BELL));
       DBUG_RETURN(0);
     }
     states+=len+1;

libmysqld/emb_qcache.cc

@@ -447,7 +447,7 @@ int emb_load_querycache_result(THD *thd, Querycache_stream *src)
   *prev_row= NULL;
   data->embedded_info->prev_ptr= prev_row;
 return_ok:
-  send_eof(thd);
+  net_send_eof(thd, thd->server_status, thd->total_warn_count);
   DBUG_RETURN(0);
 err:
   DBUG_RETURN(1);

libmysqld/emb_qcache.h

@@ -79,3 +79,4 @@ public:
 uint emb_count_querycache_size(THD *thd);
 int emb_load_querycache_result(THD *thd, Querycache_stream *src);
 void emb_store_querycache_result(Querycache_stream *dst, THD* thd);
+void net_send_eof(THD *thd, uint server_status, uint total_warn_count);

libmysqld/lib_sql.cc

@@ -87,6 +87,7 @@ emb_advanced_command(MYSQL *mysql, enum enum_server_command command,
 
   /* Clear result variables */
   thd->clear_error();
+  thd->main_da.reset_diagnostics_area();
   mysql->affected_rows= ~(my_ulonglong) 0;
   mysql->field_count= 0;
   net_clear_error(net);
@@ -625,6 +626,7 @@ int check_embedded_connection(MYSQL *mysql, const char *db)
   strmake(sctx->priv_host, (char*) my_localhost,  MAX_HOSTNAME-1);
   sctx->priv_user= sctx->user= my_strdup(mysql->user, MYF(0));
   result= check_user(thd, COM_CONNECT, NULL, 0, db, true);
+  net_end_statement(thd);
   emb_read_query_result(mysql);
   return result;
 }

sql/log.cc

@@ -280,29 +280,34 @@ void Log_to_csv_event_handler::cleanup()
 
 /* log event handlers */
 
-/*
+/**
   Log command to the general log table
 
-  SYNOPSIS
-    log_general()
+  Log given command to the general log table.
 
-    event_time        command start timestamp
-    user_host         the pointer to the string with user@host info
-    user_host_len     length of the user_host string. this is computed once
-                      and passed to all general log event handlers
-    thread_id         Id of the thread, issued a query
-    command_type      the type of the command being logged
-    command_type_len  the length of the string above
-    sql_text          the very text of the query being executed
-    sql_text_len      the length of sql_text string
+  @param  event_time        command start timestamp
+  @param  user_host         the pointer to the string with user@host info
+  @param  user_host_len     length of the user_host string. this is computed
+                            once and passed to all general log event handlers
+  @param  thread_id         Id of the thread, issued a query
+  @param  command_type      the type of the command being logged
+  @param  command_type_len  the length of the string above
+  @param  sql_text          the very text of the query being executed
+  @param  sql_text_len      the length of sql_text string
 
-  DESCRIPTION
 
-   Log given command to the general log table
+  @return This function attempts to never call my_error(). This is
+  necessary, because general logging happens already after a statement
+  status has been sent to the client, so the client can not see the
+  error anyway. Besides, the error is not related to the statement
+  being executed and is internal, and thus should be handled
+  internally (@todo: how?).
+  If a write to the table has failed, the function attempts to
+  write to a short error message to the file. The failure is also
+  indicated in the return value. 
 
-  RETURN
-    FALSE - OK
-    TRUE - error occured
+  @retval  FALSE   OK
+  @retval  TRUE    error occured
 */
 
 bool Log_to_csv_event_handler::
@@ -342,6 +347,20 @@ bool Log_to_csv_event_handler::
   table_list.db= MYSQL_SCHEMA_NAME.str;
   table_list.db_length= MYSQL_SCHEMA_NAME.length;
 
+  /*
+    1) open_performance_schema_table generates an error of the
+    table can not be opened or is corrupted.
+    2) "INSERT INTO general_log" can generate warning sometimes.
+
+    Suppress these warnings and errors, they can't be dealt with
+    properly anyway.
+
+    QQ: this problem needs to be studied in more detail.
+    Comment this 2 lines and run "cast.test" to see what's happening.
+  */
+  thd->push_internal_handler(& error_handler);
+  need_pop= TRUE;
+
   if (!(table= open_performance_schema_table(thd, & table_list,
                                              & open_tables_backup)))
     goto err;
@@ -357,14 +376,6 @@ bool Log_to_csv_event_handler::
   /* Honor next number columns if present */
   table->next_number_field= table->found_next_number_field;
 
-  /*
-    "INSERT INTO general_log" can generate warning sometimes.
-    QQ: this problem needs to be studied in more details.
-    Comment this 2 lines and run "cast.test" to see what's happening:
-  */
-  thd->push_internal_handler(& error_handler);
-  need_pop= TRUE;
-
   /*
     NOTE: we do not call restore_record() here, as all fields are
     filled by the Logger (=> no need to load default ones).

storage/myisam/ha_myisam.cc

@@ -1407,10 +1407,8 @@ int ha_myisam::enable_indexes(uint mode)
         might have been set by the first repair. They can still be seen
         with SHOW WARNINGS then.
       */
-#ifndef EMBEDDED_LIBRARY      
       if (! error)
         thd->clear_error();
-#endif /* EMBEDDED_LIBRARY */
     }
     info(HA_STATUS_CONST);
     thd->proc_info=save_proc_info;