minor fixes

Change-Id: Ib26de6527fab0113a9e1af877a52972bd4c4c57e

src/base/containers/flat_map.h

@@ -246,7 +246,6 @@ public:
     };
 
 private:
-    friend class FlatMapTest;
 template <typename _Map, typename _Element> friend class FlatMapIterator;
 template <typename _Map, typename _Element> friend class FlatMapSparseIterator;
     // True if buckets need to be resized before holding `size' elements.

src/brpc/http_method.cpp

@@ -60,7 +60,7 @@ struct LessThanByName {
 
 static void BuildHttpMethodMaps() {
     for (size_t i = 0; i < ARRAY_SIZE(g_method_pairs); ++i) {
-        int method = (int)g_method_pairs[i].method;
+        const int method = (int)g_method_pairs[i].method;
         if (method < 0 || method > (int)ARRAY_SIZE(g_method2str_map)) {
             abort();
         }