commit "mboxevent: Rewrite JSON formatting"

[Sébastien Michel]

>>
>> That requirement would rule out systems like RHEL 5, RHEL 6.
>
It is thus preferable to not require such version.
On older versions of pkg-config (<0.24), the macro will not call
AC_SUBST on generated variables <prefix>_LIBS and <prefix>_CFLAGS .
Running it twice, though, will not cause problems. I will do that.

> Is this a requirement for build from git only, or a requirement for
> build from theoretical distribution tarballs?
>
> I want the tarballs to build on old machines for sure.
>
Indeed

Sébastien