Snd 21.8

sndlib: Kjetil updated the Jack support in audio.c.

s7:  now using __has_include if it is defined (gcc has it)
       this means mus-config.h is optional in gcc/clang (you
       don't need an empty file).
     s7_make_byte_vector and friends (s7.h)
     added (*s7* 'profile-prefix), a symbol or #f
     profile-info now includes the file and line-number of the function
       and the function-local value of (*s7* 'profile-prefix), if any.
     added support for tcc (Tiny C compiler) -- no dynamic loading yet

checked: notcurses 2.4.1|3, sbcl 2.1.9

due to a blizzard of changes in notcurses, nrepl currently needs
  notcurses version 2.4.3 or later -- sorry for the inconvenience!

Thanks!: Iain Duncan, Brad Christensen, Christos Vagias, Woody Douglass,
	 James Hearon, Juan Reyes, Kjetil Matheussen
