gnu: qpdfview: Fix qt-5.15 compatibility.

* gnu/packages/pdf.scm (qpdfview)[source]: Add patch to include a missing
header.
* gnu/packages/patches/qpdfview-qt515-compat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

Signed-off-by: Leo Famulari <leo@famulari.name>

gnu/local.mk

@@ -1560,6 +1560,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/pypy3-7.3.1-fix-tests.patch		\
   %D%/packages/patches/qemu-build-info-manual.patch		\
   %D%/packages/patches/qemu-glibc-2.27.patch 			\
+  %D%/packages/patches/qpdfview-qt515-compat.patch		\
   %D%/packages/patches/qrcodegen-cpp-make-install.patch		\
   %D%/packages/patches/qt4-ldflags.patch			\
   %D%/packages/patches/qtbase-absolute-runpath.patch		\

gnu/packages/patches/qpdfview-qt515-compat.patch

@@ -0,0 +1,17 @@
+Fix compatibility with Qt 5.15.
+
+Patch copied from upstream source repository:
+
+https://bazaar.launchpad.net/~adamreichold/qpdfview/trunk/revision/2104
+
+--- a/sources/model.h	2017-04-19 21:01:25 +0000
++++ b/sources/model.h	2020-06-09 06:24:11 +0000
+@@ -24,6 +24,7 @@
+ #define DOCUMENTMODEL_H
+ 
+ #include <QList>
++#include <QPainterPath>
+ #include <QtPlugin>
+ #include <QWidget>
+ #include <QVector>
+

gnu/packages/pdf.scm

@@ -869,7 +869,8 @@ program capable of converting PDF into other formats.")
                            "trunk/" version "/+download/"
                            "qpdfview-" version ".tar.gz"))
        (sha256
-        (base32 "0v1rl126hvblajnph2hkansgi0s8vjdc5yxrm4y3faa0lxzjwr6c"))))
+        (base32 "0v1rl126hvblajnph2hkansgi0s8vjdc5yxrm4y3faa0lxzjwr6c"))
+       (patches (search-patches "qpdfview-qt515-compat.patch"))))
     (build-system gnu-build-system)
     (native-inputs
      `(("pkg-config" ,pkg-config)))