WL#2899: Add prefixes for common mysql methods

Affects: Server-7.1   —   Status: Assigned   —   Priority: Medium

The task is to add prefixes for common mysql methods
(e.g. qsort).

Rationale
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Code cleanup task requested by Monty.


Note: This task may be related to WL#438 "Add prefix 'my_' 
to heap_delete(), hash_insert(), hash_delete()".