innobase/include/os0file.h:
  Improve the comment of os_file_create_tmpfile()
innobase/os/os0file.c:
  os_file_create_tmpfile(): Use create_temp_file()
  via innobase_mysql_tmpfile() unless UNIV_HOTBACKUP is defined
sql/ha_innodb.cc:
  Added innobase_mysql_tmpfile(), a wrapper around create_temp_file()