profiling on sh

[Mark Mitchell]

> What issue were you trying to resolve with this change Mark?  Did you
> mean to kill performance of some apps?  :-(

Obviously not.

I no longer remember the details here.

I believe there was some question about whether `extern "C" memcpy' was
the same as the `std::memcpy' variant.  In other words, whether the
compiler could safely assume that the `extern "C"' version, in the
global namespace, meant what the compiler assumed it meant when treating
it as a builtin.

I believe that someone (likely Jason or Benjamin) quoted something that
suggested that it was safe to make this assumption, but that we never
acted on that.  If you file a PR, and send me email noting this
performance regression, we'll get it resolved before 3.1.

-- 
Mark Mitchell                mark@codesourcery.com
CodeSourcery, LLC            http://www.codesourcery.com