libc: Remove leftover comments

These comments refer to a comment in div.c which doesn't exist anymore.

Fixes:	7c7299df76 ("libc: Remove support for pre-C99 C standards")
Sponsored by:	Klara, Inc.

lib/libc/stdlib/imaxdiv.c

@@ -28,7 +28,6 @@
 
 #include <inttypes.h>
 
-/* See comments in div.c for implementation details. */
 imaxdiv_t
 imaxdiv(intmax_t numer, intmax_t denom)
 {

lib/libc/stdlib/ldiv.c

@@ -39,8 +39,6 @@ ldiv(long num, long denom)
 {
 	ldiv_t r;
 
-	/* see div.c for comments */
-
 	r.quot = num / denom;
 	r.rem = num % denom;
 

lib/libc/stdlib/lldiv.c

@@ -28,7 +28,6 @@
 
 #include <stdlib.h>
 
-/* See comments in div.c for implementation details. */
 lldiv_t
 lldiv(long long numer, long long denom)
 {