Export fusei timeout params via pseaudo-fs

Added two pseaudo-files to control inode's attributes in-kernel timeout,
(seconds) or disable kernel caching:

  $ cat .funex/fusei/attr_timeout  .funex/fusei/entry_timeout
  $ echo 0 > .funex/fusei/attr_timeout   # Disable
  $ echo 2 > .funex/fusei/entry_timeout  # Enable

Signed-off-by: Shachar Sharon <shachars@xxxxxx>
Control mutex kind based on build settings

Use PTHREAD_MUTEX_ERRORCHECK_NP if '-g -O0', PTHREAD_MUTEX_DEFAULT otherwise

Signed-off-by: Shachar Sharon <shachars@xxxxxx>
Tuned shutdown process: destage as much dirty as you can

Control log-debug via pseudo-fs