[PATCH] configure.ac: simplify argp check

[Mark Wielaard]

On Fri, 2020-12-11 at 03:59 +0300, Dmitry V. Levin wrote:
> Rewrite argp check using the same AC_SEARCH_LIBS based method used
> earlier in the fts check.

Thanks, that makes things nicely consistent.

Pushed,

Mark