- Set project before include GNUInstallDirs to avoid cmake warnings
- Fix RPATH to fix linking

CMake Warning (dev) at /usr/local/share/cmake/Modules/GNUInstallDirs.cmake:225 (message):
  Unable to determine default CMAKE_INSTALL_LIBDIR directory because no
  target architecture is known.  Please enable at least one language before
  including GNUInstallDirs.

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -65,7 +65,8 @@ if(APPLE)
     SET(CMAKE_MACOSX_RPATH TRUE)
     SET(CMAKE_INSTALL_RPATH "@loader_path/${INKSCAPE_INSTALL_LIBDIR_RELATIVE_TO_BINDIR}")
 else()
-    SET(CMAKE_INSTALL_RPATH "$ORIGIN/${INKSCAPE_INSTALL_LIBDIR_RELATIVE_TO_BINDIR}")
+    SET(CMAKE_INSTALL_RPATH  "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_BINDIR}"
+    "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}/inkscape")
 endif()
 
 # this can be removed if/when cmake 3.1 is made the minimum required version
