aplay, alsactl, topology: fix discards const from pointer target

aplay, alsactl, topology: fix discards const from pointer target

Since glibc-2.43:

For ISO C23, the functions bsearch, memchr, strchr, strpbrk, strrchr,
strstr, wcschr, wcspbrk, wcsrchr, wcsstr and wmemchr that return pointers
into their input arrays now have definitions as macros that return a
pointer to a const-qualified type when the input argument is a pointer
to a const-qualified type.

https://lists.gnu.org/archive/html/info-gnu/2026-01/msg00005.html

Closes: https://github.com/alsa-project/alsa-utils/pull/322
Signed-off-by: Rudi Heitbaum <rudi@heitbaum.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>