gnu: poppler: Integrate grafted update.

* gnu/packages/pdf.scm (poppler): Update to 0.56.0.
[replacement]: Remove field.
(poppler-qt4, poppler-qt5): Use (inherit) instead of (package/inherit).

gnu/packages/pdf.scm

@@ -76,15 +76,14 @@
 (define-public poppler
   (package
    (name "poppler")
-   (replacement poppler-0.56.0)
-   (version "0.52.0")
+   (version "0.56.0")
    (source (origin
             (method url-fetch)
             (uri (string-append "https://poppler.freedesktop.org/poppler-"
                                 version ".tar.xz"))
             (sha256
              (base32
-              "14hrrac2f1phi5j0qn283457w06vsp9gr075yqjrm7w370bnd2sj"))))
+              "0wviayidfv2ix2ql0d4nl9r1ia6qi5kc1nybd9vjx27dk7gvm7c6"))))
    (build-system gnu-build-system)
    ;; FIXME:
    ;;  use libcurl:        no
@@ -130,27 +129,15 @@
    (license license:gpl2+)
    (home-page "https://poppler.freedesktop.org/")))
 
-(define poppler-0.56.0
-  (package (inherit poppler)
-  (version "0.56.0")
-  (source
-    (origin
-      (method url-fetch)
-      (uri (string-append "https://poppler.freedesktop.org/poppler-"
-                          version ".tar.xz"))
-      (sha256
-       (base32
-        "0wviayidfv2ix2ql0d4nl9r1ia6qi5kc1nybd9vjx27dk7gvm7c6"))))))
-
 (define-public poppler-qt4
-  (package/inherit poppler
+  (package (inherit poppler)
    (name "poppler-qt4")
    (inputs `(("qt-4" ,qt-4)
              ,@(package-inputs poppler)))
    (synopsis "Qt4 frontend for the Poppler PDF rendering library")))
 
 (define-public poppler-qt5
-  (package/inherit poppler
+  (package (inherit poppler)
    (name "poppler-qt5")
    (inputs `(("qtbase" ,qtbase)
              ,@(package-inputs poppler)))