it can't be compile everywhere if we just cast pointer to pthread_t
So now we use correct pthread_self() value as the pthread_t and
pointer where we need to identify the thread exactly.


libmysqld/lib_sql.cc:
  pthread_self() can be used here as we use pointer to thread
  when we need to identify the thread exactly
sql/item_func.cc:
  now we use pthread_t value for thread identification in 'standalone'
  server only, in the embedded server we can use the pointer to THD
  structure