mux.c was split from utils.c in 55f9037f
and during this split all headers were simply copied without checking if
they were only needed in the part that stayed in utils.c (or whether
these haeders were needed at all). As a result quite a lot of headers
in mux.c are unnecessary. This commit removes them.
Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>