Clean up glibc version numbers in manual

[Roland McGrath]

> > It seems odd to both use move-if-change and always touch the file.
> 
> This was following what the rule immediately above does....

In that rule the target is a stamp file, not the output file.

> > If you always touch it, just do "> $@T" and "mv -f $@T $@" as usual.
> 
> Anyway, changed like that in this version.

Given that we use a stamp file for the summary and libm-err.texi, it seems
right to do it for version.texi too.

Everything else in this version looks OK to me, though I only glanced
through it quickly.


Thanks,
Roland