throne_tracker: Fix Manager sometimes not detecting KSU and optimize …

…it (#1586)

The original logic was wrong and used 3 strlen()s for every file found,
wasting cpu.

Optimize it by first comparing only the filename length, given we
already know it,
and then strncmp() to compare with "base.apk"

Tested successfully on my Bandido Kernel (4.19)

kernel/throne_tracker.c

@@ -159,8 +159,7 @@ FILLDIR_RETURN_TYPE my_actor(struct dir_context *ctx, const char *name,
 		iterate_dir(file, &sub_ctx.ctx);
 		filp_close(file, NULL);
 	} else {
-		if ((strlen(name) == strlen("base.apk")) &&
-		    (strncmp(name, "base.apk", strlen("base.apk")) == 0)) {
+		if ((namelen == 8) && (strncmp(name, "base.apk", namelen) == 0)) {
 			bool is_manager = is_manager_apk(dirpath);
 			pr_info("Found base.apk at path: %s, is_manager: %d\n",
 				dirpath, is_manager);