Correct implementation also found in Linux's soundcard.h:
https://github.com/torvalds/linux/blob/master/include/uapi/linux/soundcard.h#L1178
seq_processevent() interprets event[1] as device number and does not
work properly with current SEQ_SYSEX() implementation.
MFC after: 2 days
Sponsored by: The FreeBSD Foundation
Pull Request: https://github.com/freebsd/freebsd-src/pull/1374