gnu: librstp: Allow tests to run.

Fixes <http://bugs.gnu.org/25669>.
Reported by Maxim Cournoyer <maxim.cournoyer@gmail.com>.

Before that, the sender process in test/rtpw_test.sh would try to read
words from the parent directory, and thus it would return almost
immediately (as if it had read an empty file, no error).

* gnu/packages/telephony.scm (libsrtp)[inputs]: Add PSMISC.
[arguments]: In 'patch-dictionary-location' phase, set the name of the
'FAQ' file rather than the name of its parent directory.

gnu/packages/telephony.scm

@@ -215,7 +215,8 @@ internet.")
               (base32
                "1w2g623qkd7gdyydglx2hr4s2y237lg0nszjmy7z8d2iq8hvb9sn"))))
     (native-inputs
-     `(("procps" ,procps)))
+     `(("psmisc" ,psmisc)                        ;some tests require 'killall'
+       ("procps" ,procps)))
     (build-system gnu-build-system)
     (arguments
      '(#:test-target "runtest"
@@ -234,8 +235,8 @@ internet.")
              (substitute* "test/rtpw.c"
                (("/usr/share/dict/words")
                 (string-append (assoc-ref %build-inputs "procps")
-                               "/share/doc/procps-ng"))
-                (("words.txt") "FAQ"))
+                               "/share/doc/procps-ng/FAQ"))
+               (("words.txt") "FAQ"))
              #t)))))
     (synopsis "Secure RTP (SRTP) Reference Implementation")
     (description "This package provides an implementation of the Secure