maybe address warning

cmake -DCMAKE_BUILD_TYPE=debug -DJSONCPP_LIB_BUILD_STATIC=OFF
-DJSONCPP_LIB_BUILD_SHARED=ON -G "Visual Studio 10" ../..

`potentially uninitialized local variable 'dist' (line 2212 of
test_lib_json/main.cpp)`

src/test_lib_json/main.cpp

@@ -2203,7 +2203,7 @@ JSONTEST_FIXTURE(IteratorTest, distance) {
   Json::Value json;
   json["k1"] = "a";
   json["k2"] = "b";
-  int dist;
+  int dist = 0;
   std::string str;
   for (Json::ValueIterator it = json.begin(); it != json.end(); ++it) {
     dist = it - json.begin();