perf: optimize sanitise_LinkTable string loop

Eliminate O(N^2) overhead in sanitise_LinkTable by replacing
strlen() with a null-terminator check in the loop condition.

Co-authored-by: fangfufu <2323403+fangfufu@users.noreply.github.com>

Author: fangfufu

src/sonic.c

@@ -319,7 +319,7 @@ static void sanitise_LinkTable(LinkTable *linktbl)
             strcpy(linktbl->links[i]->linkname, "__FORWARD-SLASH__");
         }
 
-        for (size_t j = 0; j < strlen(linktbl->links[i]->linkname); j++) {
+        for (size_t j = 0; linktbl->links[i]->linkname[j] != '\0'; j++) {
             if (linktbl->links[i]->linkname[j] == '/') {
                 linktbl->links[i]->linkname[j] = '-';
             }