Use the correct patch

OBS-URL: https://build.opensuse.org/package/show/KDE:Extra/kgraphviewer?expand=0&rev=6

kgraphviewer.spec

@@ -25,6 +25,7 @@ License:        GPL-2.0 and GPL-2.0+ and LGPL-2.1+ and GPL-3.0
 Group:          Development/Tools/Other
 Url:            https://projects.kde.org/kgraphviewer
 Source0:        ftp://ftp.kde.org/pub/kde/unstable/kgraphviewer/%{version}/src/%{name}-%{version}.tar.xz
+Source1:        old_graphviz.diff
 BuildRequires:  boost-devel
 BuildRequires:  graphviz-devel
 BuildRequires:  libkde4-devel
@@ -58,13 +59,12 @@ KGraphViewer is a Graphviz dot graph file viewer for KDE
 %lang_package
 %prep
 %setup -q
-
-%build
 %if 0%{?suse_version} < 1320
-  # The patch is in the tarball
-  patch -p1 < old_graphviz.diff
+# The patch inside the tarball doesn't apply
+patch0 -p1
 %endif
 
+%build
   %cmake_kde4 -d build
   %make_jobs