Fix misleading error messages

When the upgrade process fails due to missing
either one of the files, innodb_index_stats.ibd
and innodb_table_stats.ibd, the same misleading
error was logged: "Error in renaming
mysql_index_stats_ibd".

To correctly log the error, separate the messages
for missing innodb_{index,table}_stats.ibd files
to two variables, and use the corresponding
variable during upgrade process.

All new code of the whole pull request, including
one or several files that are either new files or
modified ones, are contributed under the BSD-new
license. I am contributing on behalf of my
employer Amazon Web Services, Inc.

mysql-test/t/percona_dd_upgrade_file_per_table_off.test

@@ -3,7 +3,8 @@
 --source include/have_util_unzip.inc
 
 --disable_query_log
-call mtr.add_suppression("Error in renaming mysql_index_stats.ibd");
+call mtr.add_suppression("Missing required files mysql/innodb_index_stats.ibd.");
+call mtr.add_suppression("Missing required files mysql/innodb_table_stats.ibd.");
 call mtr.add_suppression("Resizing redo log from");
 call mtr.add_suppression("Upgrading redo log");
 call mtr.add_suppression("Starting to delete and rewrite log files");

share/messages_to_error_log.txt

@@ -3042,7 +3042,10 @@ ER_RES_GRP_SOLARIS_PROCESSOR_AFFINITY_FAILED
   eng "%s failed: processor_affinity failed (error code %d - %-.192s)."
 
 ER_DD_UPGRADE_RENAME_IDX_STATS_FILE_FAILED
-  eng "Error in renaming mysql_index_stats.ibd."
+  eng "Missing required files mysql/innodb_index_stats.ibd."
+
+ER_DD_UPGRADE_RENAME_TBL_STATS_FILE_FAILED
+  eng "Missing required files mysql/innodb_table_stats.ibd."
 
 ER_DD_UPGRADE_DD_OPEN_FAILED
   eng "Error in opening data directory %s."

sql/dd/upgrade_57/upgrade.cc

@@ -175,7 +175,7 @@ static void rename_stats_tables() {
                        table_stats.c_str(), IBD_EXT.c_str(), 0, &not_used);
 
   if (mysql_file_rename(key_file_misc, from_path, to_path, MYF(0))) {
-    LogErr(WARNING_LEVEL, ER_DD_UPGRADE_RENAME_IDX_STATS_FILE_FAILED);
+    LogErr(WARNING_LEVEL, ER_DD_UPGRADE_RENAME_TBL_STATS_FILE_FAILED);
   }
 }