libyang REFACTOR add more compiler printf attributes

Some bugs fixed because of the new warnings.
diff --git a/src/path.c b/src/path.c
index d691696..847249d 100644
--- a/src/path.c
+++ b/src/path.c
@@ -285,7 +285,7 @@
     LY_CHECK_RET(lyxp_next_token(ctx, exp, tok_idx, LYXP_TOKEN_FUNCNAME), LY_EVALID);
     if (!strncmp(&exp->expr[exp->tok_pos[*tok_idx]], "deref", 5)) {
         LOGVAL(ctx, LYVE_XPATH, "Unexpected XPath function \"%.*s\" in path, expected \"deref(...)\"",
-                exp->tok_len[*tok_idx], exp->tok_pos[*tok_idx]);
+                exp->tok_len[*tok_idx], exp->expr + exp->tok_pos[*tok_idx]);
         return LY_EVALID;
     }