971d1365ab16279bb33312583c320008e391f26e added an explicit rpath for builds of pinentry-qt. But there is already a configure option --disable-rpath. if that configure option is supplied, rpath should not be included.

See [lintian's custom-library-search-path](https://lintian.debian.org/tags/custom-library-search-path.html) warning/error for reasons why this is often not desirable with an OS/redistributor.