table to partitioned

Problem:
Crashed because usage of an uninitialised mutex when auto_incrementing
  a partitioned temporary table

Fix:
Only locking (using the mutex) if not temporary table.


mysql-test/r/partition.result:
  Bug #30878: Crashing when alter an auto_increment non partitioned
    table to partitioned
  test result
mysql-test/t/partition.test:
  Bug #30878: Crashing when alter an auto_increment non partitioned
    table to partitioned
  testcase
sql/ha_partition.cc:
  Bug #30878: Crashing when alter an auto_increment non partitioned
    table to partitioned
  
  If the table is a temporary table, the table_share->mutex is not
    initialised.
  
  Checking if not temporary table, then OK to lock (else no need
    to lock)