fix windows packaging again

CMakeLists.txt

@@ -3,7 +3,11 @@ project (thebutterflyeffect)
 
 option(WITH_DOCS "build package with(out) documentation")
 
-set (CMAKE_INSTALL_PREFIX "/usr")
+if (WIN32)
+  set (CMAKE_INSTALL_PREFIX "usr")
+else (WIN32)
+  set (CMAKE_INSTALL_PREFIX "/usr")
+endif (WIN32)
 
 set(TBE_BIN_DIR     ${CMAKE_INSTALL_PREFIX}/games)
 set(TBE_LEVELS_DIR  ${CMAKE_INSTALL_PREFIX}/share/games/tbe/levels)
@@ -56,7 +60,7 @@ IF(WIN32 AND NOT UNIX)
  SET(CPACK_RESOURCE_FILE_LICENSE "${CMAKE_CURRENT_SOURCE_DIR}\\\\COPYING")
  SET(CPACK_RESOURCE_FILE_README "${CMAKE_CURRENT_SOURCE_DIR}\\\\README.md")
  SET(CPACK_NSIS_INSTALLED_ICON_NAME "usr\\\\games/tbe.exe")
- SET(CPACK_NSIS_EXECUTABLES_DIRECTORY "games")
+ SET(CPACK_NSIS_EXECUTABLES_DIRECTORY "usr\\\\games")
  SET(CPACK_NSIS_DISPLAY_NAME "The Butterfly Effect")
  SET(CPACK_NSIS_HELP_LINK "http:\\\\\\\\www.the-butterfly-effect.org")
  SET(CPACK_NSIS_URL_INFO_ABOUT "http:\\\\\\\\www.the-butterfly-effect.org")