[PATCH v2] Do not transform strchr into rawmemchr

[Wilco Dijkstra]

Florian Weimer wrote:
> Please post a version which removes the definition of
> _HAVE_STRING_ARCH_strchr as well.

See https://sourceware.org/ml/libc-alpha/2016-11/msg00853.html
which removes all of the redundant STRING_ARCH defines.

Wilco