Fixed timing test failures.
Fixed a failure in the Aria engines page cache and log handler (found with maria.maria-big test)
- This could cause a core dump when deleting big blobs.
- Added test to end_pagecache() to verify that page cache was correctly used.
  - inc_counter_for_resize_op and dec_counter_for_resize_op are called same number of times.
  - All page cache blocks was properly deallocated (empty)


mysql-test/suite/innodb/t/innodb_bug38231.test:
  Fixed timing issue (code comment says it all)
mysql-test/suite/innodb_plugin/t/innodb_bug38231.test:
  Fixed timing issue (code comment says it all)
sql/debug_sync.cc:
  Fixed compiler warning
storage/maria/ma_loghandler.c:
  Fixed bug found by maria.maria-big test:
  - Fixed race condition between update thread logging a very big blog and checkpoint thread.
storage/maria/ma_pagecache.c:
  Added assert to ensure mutex was properly locked.
  Added test to end_pagecache() to verify that page cache was correctly used.
  - inc_counter_for_resize_op and dec_counter_for_resize_op are called same number of times.
  - All page cache blocks was properly deallocated (empty)
  In pagecache_delete_internal(), properly reset counters and pins if functions aborts.
  Added missing inc_counter_for_resize_op() to pagecache_wait_lock().
  Added missing dec_counter_for_resize_op() to pagecache_delete()