- Fixed bug in pagecache_delete_internal() when deleting block that was flushed by another thread (fixed bug when block->next_used was unexpectedly null)
Fixed some using uninitialized memory warnings found by valgrind. 

mysql-test/t/information_schema_all_engines-master.opt:
  Added options to make slow test run faster
sql/sp.cc:
  Fixed valgrind warning.
sql/sql_show.cc:
  Fixed valgrind warning.
storage/maria/ma_bitmap.c:
  Fixed wrong call parameter to pagecache_unlock_by_link() that caused assert crash in pagecache
storage/maria/ma_pagecache.c:
  Fixed possible error in pagecache_wait_lock() when hash_link was not set. (We never hit this issue, but could be possible when two threads updates the same page.
  Fixed bug in pagecache_delete_internal() when deleting block that was flushed by another thread (fixed bug when block->next_used was unexpectedly null)
  Cleanup: moved pagecache_pthread_mutex_unlock() over comments and asserts to be just before pagecache_fwrite()