config_format: fix memory leak

There can be multiple states needing to be popped in the event of
errors.

Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=61733

Signed-off-by: David Korczynski <[email protected]>

Author: DavidKorczynski

src/config_format/flb_cf_yaml.c

@@ -2039,7 +2039,9 @@ static int read_config(struct flb_cf *conf, struct local_ctx *ctx,
     }
 
     yaml_parser_delete(&parser);
-    state_pop(ctx);
+
+    /* free all remaining states */
+    while (state = state_pop(ctx));
 
     fclose(fh);
     ctx->level--;