ENH: allow for cpack stuff to be changed

CMakeLists.txt

@@ -246,17 +246,19 @@ IF(EXISTS "${CMAKE_ROOT}/Modules/CPack.cmake")
   SET(CPACK_PACKAGE_INSTALL_DIRECTORY "CMake ${CMake_VERSION_MAJOR}.${CMake_VERSION_MINOR}")
   SET(CPACK_SOURCE_PACKAGE_FILE_NAME
     "cmake-${CMake_VERSION_MAJOR}.${CMake_VERSION_MINOR}.${CMake_VERSION_PATCH}")
-  SET(CPACK_SYSTEM_NAME ${CMAKE_SYSTEM_NAME})
-  IF(${CMAKE_SYSTEM_NAME} MATCHES Windows)
+  IF(NOT DEFINED CPACK_SYSTEM_NAME)
+    SET(CPACK_SYSTEM_NAME ${CMAKE_SYSTEM_NAME})
+  ENDIF(NOT DEFINED CPACK_SYSTEM_NAME)
+  IF(${CPACK_SYSTEM_NAME} MATCHES Windows)
     IF(CMAKE_CL_64)
       SET(CPACK_SYSTEM_NAME win64)
     ELSE(CMAKE_CL_64)
       SET(CPACK_SYSTEM_NAME win32)
     ENDIF(CMAKE_CL_64)
-  ENDIF(${CMAKE_SYSTEM_NAME} MATCHES Windows)
-
-    
-  SET(CPACK_PACKAGE_FILE_NAME "${CPACK_SOURCE_PACKAGE_FILE_NAME}-${CPACK_SYSTEM_NAME}")
+  ENDIF(${CPACK_SYSTEM_NAME} MATCHES Windows)
+  IF(NOT DEFINED CPACK_PACKAGE_FILE_NAME)
+    SET(CPACK_PACKAGE_FILE_NAME "${CPACK_SOURCE_PACKAGE_FILE_NAME}-${CPACK_SYSTEM_NAME}")
+  ENDIF(NOT DEFINED CPACK_PACKAGE_FILE_NAME)
   IF(WIN32 AND NOT UNIX)
     # There is a bug in NSI that does not handle full unix paths properly. Make
     # sure there is at least one set of four (4) backlasshes.