This file is included, directly or indirectly, by most of the
kernel-space C++ code, and so importing the entirety of "std"
seriously pollutes the global namespace.
So instead, just import "std::nothrow", which is the only thing
we really want in the global namespace. Tested on both GCC2
and GCC7 and seems to work just fine.
While I'm here, also update the include guards and copyright
header to match the standard format used elsewhere.
08858e10fa