Fixed typos

- Removed duplicate words, like "the the" and "to to"
- Removed duplicate lines (one double sort line found in mysql.cc)
- Fixed some typos found while searching for duplicate words.

Command used to find duplicate words:
egrep -rI "\s([a-zA-Z]+)\s+\1\s" | grep -v param

Thanks to Artjoms Rimdjonoks for the command and pointing out the
spelling errors.

sql/sql_class.cc

@@ -2080,7 +2080,7 @@ void THD::disconnect()
 
 #ifdef SIGNAL_WITH_VIO_CLOSE
   /*
-    Since a active vio might might have not been set yet, in
+    Since a active vio might have not been set yet, in
     any case save a reference to avoid closing a inexistent
     one or closing the vio twice if there is a active one.
   */
@@ -8083,7 +8083,7 @@ int THD::binlog_query(THD::enum_binlog_query_type qtype, char const *query_arg,
 
   The filter is in decide_logging_format() to mark queries to not be stored
   in the binary log, for example by a shared distributed engine like S3.
-  This function resets the filter to ensure the the query is logged if
+  This function resets the filter to ensure the query is logged if
   the binlog is active.
 
   Note that 'direct' is set to false, which means that the query will