gnu: pcb: Drop input labels.

* gnu/packages/engineering.scm (pcb)[inputs, native-inputs]: Remove package
labels.

gnu/packages/engineering.scm

@@ -441,26 +441,26 @@ features.")))
               (system "Xvfb :1 &")
               (setenv "DISPLAY" ":1"))))))
     (inputs
-     `(("dbus" ,dbus)
+     (list dbus
-       ("mesa" ,mesa)
+           mesa
-       ("udev" ,eudev) ;FIXME: required by mesa
+           eudev                        ;FIXME: required by mesa
-       ("glu" ,glu)
+           glu
-       ("gd" ,gd)
+           gd
-       ("gtk" ,gtk+-2)
+           gtk+-2
-       ("gtkglext" ,gtkglext)
+           gtkglext
-       ("shared-mime-info" ,shared-mime-info)
+           shared-mime-info
-       ("tk" ,tk)))
+           tk))
     (native-inputs
-     `(("pkg-config" ,pkg-config)
+     (list bison
-       ("intltool" ,intltool)
+           desktop-file-utils
-       ("bison" ,bison)
+           flex
-       ("desktop-file-utils" ,desktop-file-utils)
+           intltool
-       ("flex" ,flex)
+           pkg-config
-       ;; For tests
+           ;; For tests
-       ("imagemagick" ,imagemagick)
+           imagemagick
-       ("gerbv" ,gerbv)
+           gerbv
-       ("ghostscript" ,ghostscript)
+           ghostscript
-       ("xvfb" ,xorg-server-for-tests)))
+           xorg-server-for-tests))
     (home-page "http://pcb.geda-project.org/")
     (synopsis "Design printed circuit board layouts")
     (description