WL#1761: Make --sync-frm to ignore temporary tables

Affects: Server-5.0   —   Status: Complete   —   Priority: Medium

We have --sync-frm option (default) which makes .frm to be be flushed by fsync() 
after creation/modification.

This especially hurts badly for explicit temporary tables, which are frequently
created and droppend.   There is also no reason to fsync their .frm file due to
their short lifetime.

Resume: We need to disable fsyncing .frm for temporary tables, created as