Use GNUInstallDirs to install arch-independent data (hluk#1037)

This allows better control on installation directories which helps on
distributions with multiarch layout. Executables and libraries go into
/usr/arch/{bin,lib} and architecture independent files will be installed in /usr/share.

CMakeLists.txt

@@ -18,16 +18,18 @@ OPTION(PEDANTIC "Enable all compiler warnings" OFF)
 # Options (cmake -LH)
 OPTION(WITH_TESTS "Run test cases from command line" ${COPYQ_DEBUG})
 OPTION(WITH_PLUGINS "Compile plugins" ON)
+
 # Unix-specific options
 if (UNIX AND NOT APPLE)
+    include(GNUInstallDirs)
     set(PLUGIN_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}/${CMAKE_SHARED_MODULE_PREFIX}/copyq/plugins" CACHE PATH "Install path for plugins")
-    set(ICON_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}/share/icons/hicolor/scalable/apps" CACHE PATH "Install path for icons")
-    set(ICON_INSTALL_PREFIX_TEMPLATE "${CMAKE_INSTALL_PREFIX}/share/icons/hicolor/%SIZE%/apps" CACHE PATH "Install path for icons (%SIZE% is icon size)")
-    set(THEME_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}/share/copyq/themes" CACHE PATH "Install path for themes")
-    set(DESKTOP_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}/share/applications" CACHE PATH "Install path for desktop file")
-    set(APPDATA_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}/share/metainfo" CACHE PATH "Install path for AppData file")
-    set(MANPAGE_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}/share/man/man1" CACHE PATH "Install path for manual pages")
-    set(TRANSLATION_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}/share/copyq/translations" CACHE PATH "Install path for translations")
+    set(ICON_INSTALL_PREFIX "${CMAKE_INSTALL_DATAROOTDIR}/icons/hicolor/scalable/apps" CACHE PATH "Install path for icons")
+    set(ICON_INSTALL_PREFIX_TEMPLATE "${CMAKE_INSTALL_DATAROOTDIR}/icons/hicolor/%SIZE%/apps" CACHE PATH "Install path for icons (%SIZE% is icon size)")
+    set(THEME_INSTALL_PREFIX "${CMAKE_INSTALL_DATAROOTDIR}/copyq/themes" CACHE PATH "Install path for themes")
+    set(DESKTOP_INSTALL_PREFIX "${CMAKE_INSTALL_DATAROOTDIR}/applications" CACHE PATH "Install path for desktop file")
+    set(APPDATA_INSTALL_PREFIX "${CMAKE_INSTALL_DATAROOTDIR}/metainfo" CACHE PATH "Install path for AppData file")
+    set(MANPAGE_INSTALL_PREFIX "${CMAKE_INSTALL_MANDIR}/man1" CACHE PATH "Install path for manual pages")
+    set(TRANSLATION_INSTALL_PREFIX "${CMAKE_INSTALL_DATAROOTDIR}/copyq/translations" CACHE PATH "Install path for translations")
     set(ICON_NAME "copyq" CACHE STRING "Name for icon files")
 endif()