Get correct major opcode for MIT-SHM instead of an hard-coded one that
works with some X servers (not including mine).

mode by default. Packagers and build bots should re-enable it with:
./configure --enable-fast-install

queuing any data - this is mostly useful when quitting

 - vlc_object_lock, vlc_object_unlock: take/release object_lock
 - vlc_object_signal: trigger object_wait
 - vlc_object_wait, vlc_object_timedwait: wait on object_wait