[core] Fix out of range exception for string compare

platform/default/local_file_source.cpp

@@ -75,7 +75,7 @@ std::unique_ptr<AsyncRequest> LocalFileSource::request(const Resource& resource,
 }
 
 bool LocalFileSource::acceptsURL(const std::string& url) {
-    return std::equal(fileProtocol.begin(), fileProtocol.end(), url.begin());
+    return 0 == url.rfind(fileProtocol, 0);
 }
 
 } // namespace mbgl