Improve generic stpcpy performance

[Carlos O'Donell]

On 12/22/2014 06:39 AM, Richard Earnshaw wrote:
> I noticed while going through some benchmark results that the generic
> stpcpy was substantially slower than the simple_stpcpy in the benchmark
> itself.
> 
> So, similar to Wilko's recent strcpy patch, this patch uses the same
> approach for stpcpy.
> 
> Note that it does not help to use mempcpy, since that returns a value
> that points beyond the end of the copied data.
> 
> OK?
> 
> 	* string/stpcpy.c (__stpcpy): Rewrite using strlen and memcpy.
> 

Please check this in. Thanks for making the generic routines faster.
They will all soon depend on a fast memcpy, but that's almost expected.

Cheers,
Carlos.