sort: Const correctness for C23

On some platforms, e.g. Linux Clang 22.1.8 / glibc 2.43, strchr()
now implements the C23 behaviour where passing a const pointer to
strchr() also returns a const pointer.  This breaks sort during
the bootstrap build, since it assumes the return value is always
a mutable pointer.

As the returned pointer is never used to modify the value, fix this
by making the temporary variable const.

MFC after:	1 week
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D58491

1 files changed, 1 insertions, 1 deletions

diff --git a/usr.bin/sort/sort.c b/usr.bin/sort/sort.c
index 6e4023c43063..422884573ae9 100644
--- a/usr.bin/sort/sort.c
+++ b/usr.bin/sort/sort.c
@@ -735,7 +735,7 @@ parse_k(const char *s, struct key_specs *ks)
 	    { false, false, false, false, false, false };
 
 	if (s && *s) {
-		char *sptr;
+		const char *sptr;
 
 		sptr = strchr(s, ',');
 		if (sptr) {