Bugfix:

Bugfix:
 - dead SMP lock in es1968 (maestro2) driver.

Bugfix & enhances of sequencer stuff
    by Scott McNab <sdm@fractalgraphics.com.au>:
 - fix for the insrument list locking in SND_SEQ_EVENT_INSTR_BEGIN
   and SND_SEQ_EVENT_INSTR_END events.
   Note that nothing seems to really take notice of the list locking.
   This is more an issue when we add support for editing instruments
   anyway.

 - added new alsa-lib utility function snd_seq_ev_set_varusr() which
   is similar to snd_seq_ev_set_variable(), but specifies userspace
   extended event data.
   This is required in order to use the SND_SEQ_EVENT_INSTR_PUT
   command (took me bloody ages to work this out btw)

 - minor correction for gus & trident synth drivers