guix package: '-s' displays different packages that have the same location.

guix package: '-s' displays different packages that have the same location.

Before that, 'guix package -s foobarbaz' would display only one package
when several match but they have the same location (which is common when
using 'inherit'.)

The original rationale was given at
<http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00280.html> but
it was arguably misguided because it led to "real" packages being
hidden.

Reported by Tomáš Čech <sleep_walker@gnu.org>.

* guix/scripts/package.scm (find-packages-by-description)[same-location?]:
  Remove.
  Remove call to 'delete-duplicates'.