gnu: vmpk: Remove package.

The vmpk package has been broken for a while and attempts to fix it have
failed.  The package "jack-keyboard" offers similar features.

* gnu/packages/music.scm (vmpk): Remove variable.

gnu/packages/music.scm

@@ -1364,53 +1364,6 @@ multiplatform realtime MIDI I/O library is also provided with various output
 backends, including ALSA, OSS, Network and FluidSynth.")
     (license license:gpl2+)))
 
-(define-public vmpk
-  (package
-    (name "vmpk")
-    (version "0.6.2a")
-    (source (origin
-              (method url-fetch)
-              (uri (string-append "mirror://sourceforge/vmpk/vmpk/"
-                                  (string-drop-right version 1)
-                                  "/vmpk-" version ".tar.bz2"))
-              (sha256
-               (base32
-                "0259iikvxnfdiifrh02g8xgcxikrkca4nhd3an8xzx0bd6bk8ifi"))))
-    (build-system cmake-build-system)
-    (arguments
-     `(#:tests? #f  ; no test target
-       #:phases
-       (modify-phases %standard-phases
-         (add-before 'configure 'fix-docbook
-           (lambda* (#:key inputs #:allow-other-keys)
-             (substitute* "cmake_admin/CreateManpages.cmake"
-               (("http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl")
-                (string-append (assoc-ref inputs "docbook-xsl")
-                               "/xml/xsl/docbook-xsl-"
-                               ,(package-version docbook-xsl)
-                               "/manpages/docbook.xsl")))
-             #t)))))
-    (inputs
-     `(("drumstick" ,drumstick)
-       ("qtbase" ,qtbase)
-       ("qtsvg" ,qtsvg)
-       ("qttools" ,qttools)
-       ("qtx11extras" ,qtx11extras)))
-    (native-inputs
-     `(("libxslt" ,libxslt) ;for xsltproc
-       ("docbook-xsl" ,docbook-xsl)
-       ("pkg-config" ,pkg-config)))
-    (home-page "http://vmpk.sourceforge.net")
-    (synopsis "Virtual MIDI piano keyboard")
-    (description
-     "Virtual MIDI Piano Keyboard is a MIDI events generator and receiver.  It
-doesn't produce any sound by itself, but can be used to drive a MIDI
-synthesizer (either hardware or software, internal or external).  You can use
-the computer's keyboard to play MIDI notes, and also the mouse.  You can use
-the Virtual MIDI Piano Keyboard to display the played MIDI notes from another
-instrument or MIDI file player.")
-    (license license:gpl3+)))
-
 (define-public zynaddsubfx
   (package
     (name "zynaddsubfx")