Address the case in which GAME_BINDIR is set to an absolute path

Author: alemart

CMakeLists.txt

@@ -117,8 +117,8 @@ SET(SURGESCRIPT_INCLUDE_PATH "${CMAKE_INCLUDE_PATH}" CACHE PATH "Where to look f
 SET(PHYSFS_LIBRARY_PATH "${CMAKE_LIBRARY_PATH}" CACHE PATH "Where to look for PhysicsFS")
 SET(PHYSFS_INCLUDE_PATH "${CMAKE_INCLUDE_PATH}" CACHE PATH "Where to look for the header files of PhysicsFS")
 IF(UNIX)
-  SET(GAME_BINDIR "games" CACHE PATH "Directory in which the game executable will installed (to be appended to CMAKE_INSTALL_PREFIX)")
-  SET(GAME_DATADIR "share/games/${GAME_UNIXNAME}" CACHE PATH "Directory in which the game data will be installed")
+  SET(GAME_BINDIR "games" CACHE PATH "Directory in which the game executable will installed (will be appended to CMAKE_INSTALL_PREFIX if it's a relative path)")
+  SET(GAME_DATADIR "share/games/${GAME_UNIXNAME}" CACHE PATH "Directory in which the game data will be installed (will be appended to CMAKE_INSTALL_PREFIX if it's a relative path)")
   SET(GAME_USERDIRNAME "${GAME_UNIXNAME}" CACHE PATH "Name of the user-modifiable asset directory")
   IF(NOT ANDROID)
     SET(DESKTOP_ICON_PATH "/usr/share/pixmaps" CACHE PATH "Where to install the icon file")
@@ -163,7 +163,12 @@ generate_file("credits.c")
 # They require the absolute path of the icon
 IF(DEFINED DESKTOP_ICON_PATH)
   CMAKE_PATH(APPEND DESKTOP_ICON_FULLPATH "${DESKTOP_ICON_PATH}" "opensurge.png")
-  CMAKE_PATH(APPEND DESKTOP_EXEC_FULLPATH "${CMAKE_INSTALL_PREFIX}" "${GAME_BINDIR}" "${GAME_UNIXNAME}")
+  IF(IS_ABSOLUTE "${GAME_BINDIR}")
+    CMAKE_PATH(APPEND DESKTOP_EXEC_FULLPATH "${GAME_BINDIR}" "${GAME_UNIXNAME}")
+  ELSE()
+    CMAKE_PATH(APPEND DESKTOP_EXEC_FULLPATH "${CMAKE_INSTALL_PREFIX}" "${GAME_BINDIR}" "${GAME_UNIXNAME}")
+  ENDIF()
+
   generate_file("opensurge.desktop")
   generate_file("opensurge.appdata.xml")
 ENDIF()