Make internal func anon

fixes #489
diff --git a/include/json/config.h b/include/json/config.h
index 606cc85..085bdc0 100644
--- a/include/json/config.h
+++ b/include/json/config.h
@@ -80,7 +80,7 @@
 // In c++11 the override keyword allows you to explicity define that a function
 // is intended to override the base-class version.  This makes the code more
 // managable and fixes a set of common hard-to-find bugs.
-#if __cplusplus >= 201103L 
+#if __cplusplus >= 201103L
 # define JSONCPP_OVERRIDE override
 #elif defined(_MSC_VER) && _MSC_VER > 1600
 # define JSONCPP_OVERRIDE override
diff --git a/src/lib_json/json_writer.cpp b/src/lib_json/json_writer.cpp
index 09cbcfa..35f0b1f 100644
--- a/src/lib_json/json_writer.cpp
+++ b/src/lib_json/json_writer.cpp
@@ -135,6 +135,7 @@
 
 #endif // # if defined(JSON_HAS_INT64)
 
+namespace {
 JSONCPP_STRING valueToString(double value, bool useSpecialFloats, unsigned int precision) {
   // Allocate a buffer that is more than large enough to store the 16 digits of
   // precision requested below.
@@ -164,6 +165,7 @@
   fixNumericLocale(buffer, buffer + len);
   return buffer;
 }
+}
 
 JSONCPP_STRING valueToString(double value) { return valueToString(value, false, 17); }