Clang++ 3.6 and g++ (4.7.2) cannot find std::stoll

[Peter Sommerfeld]

Using DFLY 4.03 and compiling with clang++3.6 as well as with g++ 
(-std=c++11)  the compilers reports an error when trying to call 
functions std::stoll() or std::to_string() of <string>:
"no member named 'stoll' in namspace 'std'".
String members work as expected. Any pointer what is wrong here
and what can be done ?

Peter