Fix build galera with std::shared_ptr

[klirichek]

Default scons configuration provides '-ansi' flag to g++ compiler, which actually means '-std=c++98'. So, later tests for c++11 features always fails and build finaly is always based on TR1/Boost implementations.

Rewriting this flag to '-std=c++11' effectively invokes std library instead, but galera then fails to build because of using for_each without explicitly included (it seems that boost shared_ptr replacement uses it for own purposes, and pollutes global scope).