Fixed bug where return value 'error' was not set in case of error in pagecache
Documented the open LOAD INDEX bug


KNOWN_BUGS.txt:
  Added the problem with LOAD INDEX as a known bugs. Will fix this bug later this week
storage/maria/ma_pagecache.c:
  Fixed portability issue with comparing thread id
  Fixed bug where return value 'error' was not set in case of error