C++11 is optional otherwise build without C++ will fail on:
checking whether no supports C++11 features with -std=gnu++11... no
checking whether no supports C++11 features with -std=gnu++0x... no
checking whether no supports C++11 features with -std=c++11... no
checking whether no supports C++11 features with +std=c++11... no
checking whether no supports C++11 features with -h std=c++11... no
checking whether no supports C++11 features with -std=c++0x... no
checking whether no supports C++11 features with +std=c++0x... no
checking whether no supports C++11 features with -h std=c++0x... no
configure: error: *** A compiler with support for C++11 language features is required.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>