moved std::to_string to util.h from android

ClientContext.cpp

@@ -8,12 +8,6 @@
 #include "Identity.h"
 #include "ClientContext.h"
 
-#ifdef ANDROID
-#  include "to_string.h"
-#else
-#  define to_string(x) std::to_string(x)
-#endif
-
 namespace i2p
 {
 namespace client
@@ -298,7 +292,7 @@ namespace client
 	template<typename Section, typename Type>
 	std::string ClientContext::GetI2CPOption (const Section& section, const std::string& name, const Type& value) const
 	{
-        return section.second.get (boost::property_tree::ptree::path_type (name, '/'), to_string (value));
+        return section.second.get (boost::property_tree::ptree::path_type (name, '/'), std::to_string (value));
 	}	
 
 	template<typename Section>