[m-rev.] for review: Use format string to build path in io.do_make_temp.

[Zoltan Somogyi]

On Wed, 19 Sep 2018 10:35:40 +1000, Peter Wang <novalazy at gmail.com> wrote:
> This should fix Mantis bug #469, where gcc emits a warning for a call to
> strncat, breaking the build.
> 
> library/io.m:
>     Simplify the non-mkstemp branch of io.do_make_temp by building the
>     temporary path with MR_make_string() instead of a combination of
>     strcpy/strcat/strncat. This was already the case in the mkstemp
>     branch.
> 
>     Be more precise in the documentation of io.make_temp_file regarding
>     the truncation of the Prefix argument. Give notification that the
>     behaviour is subject to change.

The diff looks fine.

Zoltan.