Description: Add support for Multi-Arch to CMake
Author: Olek Wojnar <olekw.dev@gmail.com>
Last-Update: 2019-12-12

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,6 +27,7 @@
 set (CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PROJECT_SOURCE_DIR}/cmake")
 include(CEGUIMacros)
 include(CMakeDependentOption)
+include(GNUInstallDirs)
 
 ################################################################################
 # Set up version information
@@ -583,13 +584,7 @@
 set (CMAKE_RUNTIME_OUTPUT_DIRECTORY_RELWITHDEBINFO ${CMAKE_RUNTIME_OUTPUT_DIRECTORY})
 
 # set up install sub-directories
-if (CMAKE_SIZEOF_VOID_P EQUAL 8 AND EXISTS "${CMAKE_INSTALL_PREFIX}/lib64")
-    set( CEGUI_LIB_INSTALL_DIR lib64 )
-elseif (CMAKE_SIZEOF_VOID_P EQUAL 4 AND EXISTS "${CMAKE_INSTALL_PREFIX}/lib32")
-    set( CEGUI_LIB_INSTALL_DIR lib32 )
-else()
-    set( CEGUI_LIB_INSTALL_DIR lib )
-endif()
+set( CEGUI_LIB_INSTALL_DIR "${CMAKE_INSTALL_LIBDIR}" )
 
 set( CEGUI_VER_INSTALL_SUBDIR "/${CMAKE_PROJECT_NAME}-${CEGUI_VERSION_MAJOR}" )
 set( CEGUI_DATA_INSTALL_DIR "share${CEGUI_VER_INSTALL_SUBDIR}.${CEGUI_VERSION_MINOR}.${CEGUI_VERSION_PATCH}" )
@@ -598,7 +593,7 @@
 set( CEGUI_PKGCONFIG_INSTALL_DIR "${CEGUI_LIB_INSTALL_DIR}/pkgconfig" )
 set( CEGUI_MODULE_INSTALL_DIR "${CEGUI_LIB_INSTALL_DIR}/${CMAKE_PROJECT_NAME}-${CEGUI_VERSION_MAJOR}.${CEGUI_VERSION_MINOR}" )
 set( CEGUI_SAMPLE_INSTALL_DIR "${CEGUI_MODULE_INSTALL_DIR}" ) # TODO: put into /samples subdir!
-set( CEGUI_INCLUDE_INSTALL_DIR "include${CEGUI_VER_INSTALL_SUBDIR}.${CEGUI_VERSION_MINOR}.${CEGUI_VERSION_PATCH}" )
+set( CEGUI_INCLUDE_INSTALL_DIR "include/${CMAKE_LIBRARY_ARCHITECTURE}${CEGUI_VER_INSTALL_SUBDIR}.${CEGUI_VERSION_MINOR}.${CEGUI_VERSION_PATCH}" )
 
 ################################################################################
 # Deal with files we generate from template files