gnu: plasma-framework: Fix build errors in dependent packages.

Fix build errors in dependent packages if PREFIX is different from ECM's
PREFIX - which is the case in Guix.  See <https://bugs.kde.org/424483> for
details.

* gnu/packages/patches/plasma-framework-fix-KF5PlasmaMacros.cmake.patch: New
  file.
* gnu/local.mk (dist_patch_DATA) Add it.
* packages/kde-frameworks.scm (plasma-framework)[source]: Use this patch.

gnu/local.mk

@@ -1410,6 +1410,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/pam-mount-luks2-support.patch		\
   %D%/packages/patches/pango-skip-libthai-test.patch		\
   %D%/packages/patches/pciutils-hurd-configure.patch		\
+  %D%/packages/patches/plasma-framework-fix-KF5PlasmaMacros.cmake.patch \
   %D%/packages/patches/ppsspp-disable-upgrade-and-gold.patch		\
   %D%/packages/patches/samba-fix-fcntl-hint-detection.patch		\
   %D%/packages/patches/sdl-pango-api_additions.patch		\

gnu/packages/kde-frameworks.scm

@@ -3449,7 +3449,8 @@ setUrl, setUserAgent and call.")
                     name "-" version ".tar.xz"))
               (sha256
                (base32
-                "06cxajsxj62g3c37ssrrcaxb9a12zbyp2kvrjqym329k5vd89272"))))
+                "06cxajsxj62g3c37ssrrcaxb9a12zbyp2kvrjqym329k5vd89272"))
+              (patches (search-patches "plasma-framework-fix-KF5PlasmaMacros.cmake.patch"))))
     (build-system cmake-build-system)
     (propagated-inputs
      `(("kpackage" ,kpackage)

gnu/packages/patches/plasma-framework-fix-KF5PlasmaMacros.cmake.patch

@@ -0,0 +1,25 @@
+From ff5ed26f21d304e867ab57781878069567deb23d Mon Sep 17 00:00:00 2001
+From: Hartmut Goebel <h.goebel@crazy-compilers.com>
+Date: Mon, 3 Aug 2020 19:49:58 +0000
+Subject: [PATCH] Fix build errors if PREFIX is different from ECM's PREFIX.
+
+See <https://bugs.kde.org/424483> for details
+---
+ KF5PlasmaMacros.cmake | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff --git a/KF5PlasmaMacros.cmake b/KF5PlasmaMacros.cmake
+index 494b42d56..80b3fd8dd 100644
+--- a/KF5PlasmaMacros.cmake
++++ b/KF5PlasmaMacros.cmake
+@@ -1,6 +1,5 @@
+ 
+-find_package(ECM 1.6.0 CONFIG REQUIRED)
+-include(${ECM_KDE_MODULE_DIR}/KDEInstallDirs.cmake)
++include(KDEInstallDirs)
+ 
+ set(PLASMA_RELATIVE_DATA_INSTALL_DIR "plasma")
+ set(PLASMA_DATA_INSTALL_DIR "${KDE_INSTALL_DATADIR}/${PLASMA_RELATIVE_DATA_INSTALL_DIR}")
+-- 
+GitLab
+