fix c++11 compiler errors below
fix c++11 compiler errors below

/usr/include/c++/4.9/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
pombredanne/pyre2,pombredanne/pyre2,axiak/pyre2,axiak/pyre2,pombredanne/pyre2