Use these mkspecs to switch to the new libc++ C++ runtime library, which
in turn makes it possible to enable C++11 support with clang.
Change-Id: If92908592f8bee4829a1bad747fe396f527d26c7
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
