toolbox: turn on -Werror

- Deal with some signedness issues
- Deal with some size issues
- Deal with NULL pointer issues
- Deal with some -Wunused issues

Change-Id: I1479dd90d690084491bae3475f2c547833519a57
diff --git a/toolbox/load_policy.c b/toolbox/load_policy.c
index eb5aba6..90d48c4 100644
--- a/toolbox/load_policy.c
+++ b/toolbox/load_policy.c
@@ -10,7 +10,7 @@
 
 int load_policy_main(int argc, char **argv)
 {
-    int fd, rc, vers;
+    int fd, rc;
     struct stat sb;
     void *map;
     const char *path;