modpost: explain why we can't use strsep

Mention why we open-code strsep, so it is clear that it is intentional.

Fixes: 736bb118 ("modpost: remove use of non-standard strsep() in HOSTCC code")
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/mod/modpost.c

@@ -144,6 +144,7 @@ char *get_line(char **stringp)
 	if (!orig || *orig == '\0')
 		return NULL;
 
+	/* don't use strsep here, it is not available everywhere */
 	next = strchr(orig, '\n');
 	if (next)
 		*next++ = '\0';