[m-rev.] for review: Require readline/editline header files to use the libraries.

[Peter Wang]

On Tue, 4 Jun 2019 15:58:17 +1000 (AEST), Julien Fischer <jfischer at opturion.com> wrote:
> 
> 
> On Tue, 4 Jun 2019, Peter Wang wrote:
> 
> Add a summary line (e.g. the subject of this mail) to the start of the
> log message; it looks strange in git log otherwise
> 
> > m4/mercury.m4:
> >    Require readline headers in order to use the readline library.
> >
> >    Require editline header in order to use the editline library.
> 
> 
> What's the rationale for this change?

To avoid compilation errors on systems with the readline library
installed but not the headers.

Peter