Ordering dependency between string.h and strings.h.

[Paul Brook]

> > As far as I know
> > there were two sets of functions for the same thing, present on
> > different systems, and the reasonably named one was chosen as the
> > standard one.
>
> The reasonably named ones are index() and rindex().  Note the existence of
> string.index() and string.rindex() in python:

Also not that some libstdc++ objects have an index() method, so defining 
index(...) as a macro does not work. This currently breaks if you welect 
whichever combination of uclibc options make it define index() as a macro.

Paul