gnu: twolame: Make the test suite compatible with Perl 5.24.

* gnu/packages/audio.scm (twolame)[source]: Add snippet to fix test.

gnu/packages/audio.scm

@@ -2134,7 +2134,15 @@ conversion.  It may be used, for example, to resample PCM-encoded audio.")
        (uri (string-append "mirror://sourceforge/twolame/twolame/" version
                            "/twolame-" version ".tar.gz"))
        (sha256
-        (base32 "0ahiqqng5pidwhj1wzph4vxxgxxgcfa3gl0gywipzx2ii7s35wwq"))))
+        (base32 "0ahiqqng5pidwhj1wzph4vxxgxxgcfa3gl0gywipzx2ii7s35wwq"))
+       (modules '((guix build utils)))
+       ;; The tests break with Perl 5.24:
+       ;; https://github.com/njh/twolame/issues/21
+       ;; TODO: Remove this snippet when upgrading twolame.
+       (snippet
+        '(begin
+           (substitute* "tests/test.pl" (("\\(@_\\)") "($_[0])"))
+           #t))))
     (build-system gnu-build-system)
     (inputs
      `(("libsndfile" ,libsndfile)))