COMP: Avoid continuous rebuild of ExternalPackages

New option added to that defaults to off for FORCE_EXTERNAL_BUILDS.
This needs to be turned ON to allow updating of external packages.

Needed to split the ExternalProject command and argument into separate
varables for their effect to work.  Otherwise they were having no
noticiable effect on the build system.

SuperBuild.cmake

@@ -17,10 +17,10 @@ include(${CMAKE_CURRENT_SOURCE_DIR}/Common.cmake)
 #-----------------------------------------------------------------------------
 # Git protocol option
 #-----------------------------------------------------------------------------
-option(${CMAKE_PROJECT_NAME}_USE_GIT_PROTOCOL "For development, turn this on to use the git protocol instead." OFF)
-set(git_protocol "http")
-if( ${CMAKE_PROJECT_NAME}_USE_GIT_PROTOCOL)
-  set(git_protocol "git")
+option(${CMAKE_PROJECT_NAME}_USE_GIT_PROTOCOL "If behind a firewall turn this off to use http instead." ON)
+set(git_protocol "git")
+if(NOT ${CMAKE_PROJECT_NAME}_USE_GIT_PROTOCOL)
+  set(git_protocol "http")
 endif()
 
 find_package(Git REQUIRED)
@@ -45,6 +45,19 @@ else()
   set(gen "${CMAKE_GENERATOR}")
 endif()
 
+
+# With CMake 2.8.9 or later, the UPDATE_COMMAND is required for updates to occur.
+# For earlier versions, we nullify the update state to prevent updates and
+# undesirable rebuild.
+option(FORCE_EXTERNAL_BUILDS "Force rebuilding of external project (if they are updated)" OFF)
+if(CMAKE_VERSION VERSION_LESS 2.8.9 OR NOT FORCE_EXTERNAL_BUILDS)
+  set(cmakeversion_external_update UPDATE_COMMAND)
+  set(cmakeversion_external_update_value "" )
+else()
+  set(cmakeversion_external_update LOG_UPDATE )
+  set(cmakeversion_external_update_value 1)
+endif()
+
 #-----------------------------------------------------------------------------
 # Platform check
 #-----------------------------------------------------------------------------
@@ -80,6 +93,8 @@ CMAKE_DEPENDENT_OPTION(
   "BUILD_STYLE_UTILS" OFF
   )
 
+set(EXTERNAL_PROJECT_BUILD_TYPE "Release" CACHE STRING "Default build type for support libraries")
+
 option(USE_SYSTEM_ITK "Build using an externally defined version of ITK" OFF)
 option(USE_SYSTEM_SlicerExecutionModel "Build using an externally defined version of SlicerExecutionModel"  OFF)
 
@@ -179,7 +194,9 @@ list(APPEND ${CMAKE_PROJECT_NAME}_SUPERBUILD_EP_VARS
 
 _expand_external_project_vars()
 set(COMMON_EXTERNAL_PROJECT_ARGS ${${CMAKE_PROJECT_NAME}_SUPERBUILD_EP_ARGS})
-SlicerMacroCheckExternalProjectDependency(${LOCAL_PROJECT_NAME})
+set(extProjName ${LOCAL_PROJECT_NAME})
+set(proj        ${LOCAL_PROJECT_NAME})
+SlicerMacroCheckExternalProjectDependency(${proj})
 
 #-----------------------------------------------------------------------------
 # Set CMake OSX variable to pass down the external project

SuperBuild/External_Boost.cmake

@@ -8,7 +8,7 @@ ExternalProject_add(Boost
 #  URL http://sourceforge.net/projects/boost/files/boost/1.49.0/boost_1_49_0.tar.gz
 #  URL_MD5 e0defc8c818e4f1c5bbb29d0292b76ca
   SOURCE_DIR Boost
-  "${cmakeversion_external_update}"
+  ${cmakeversion_external_update} "${cmakeversion_external_update_value}"
   CONFIGURE_COMMAND ${CMAKE_COMMAND}
   -DBUILD_DIR:PATH=${CMAKE_CURRENT_BINARY_DIR}/Boost
   -DBOOST_INSTALL_DIR:PATH=${Boost_Install_Dir}

SuperBuild/External_Cppcheck.cmake

@@ -28,7 +28,7 @@ if(NOT DEFINED Cppcheck_EXE AND NOT ${USE_SYSTEM_Cppcheck})
     GIT_TAG ${Cppcheck_GIT_TAG}
     SOURCE_DIR ${proj}
     BUILD_IN_SOURCE 1
-    ${cmakeversion_external_update}
+    ${cmakeversion_external_update} "${cmakeversion_external_update_value}"
     CONFIGURE_COMMAND ""
     BUILD_COMMAND HAVE_RULES=no ${CMAKE_MAKE_PROGRAM}
     INSTALL_COMMAND HAVE_RULES=no DESTDIR=${CMAKE_BINARY_DIR}/ PREFIX=Utils ${CMAKE_MAKE_PROGRAM} install

SuperBuild/External_ITKv4.cmake

@@ -87,7 +87,7 @@ if(NOT DEFINED ${extProjName}_DIR AND NOT ${USE_SYSTEM_${extProjName}})
     GIT_TAG ${${proj}_GIT_TAG}
     SOURCE_DIR ${proj}
     BINARY_DIR ${proj}-build
-    "${cmakeversion_external_update}"
+    ${cmakeversion_external_update} "${cmakeversion_external_update_value}"
     CMAKE_GENERATOR ${gen}
     CMAKE_ARGS
       -Wno-dev

SuperBuild/External_KWStyle.cmake

@@ -34,7 +34,7 @@ if(NOT DEFINED KWStyle_EXE AND NOT ${USE_SYSTEM_KWStyle})
     CVS_MODULE KWStyle
     SOURCE_DIR ${proj}
     BINARY_DIR ${proj}-build
-    ${cmakeversion_external_update}
+    ${cmakeversion_external_update} "${cmakeversion_external_update_value}"
     CMAKE_ARGS
       ${CMAKE_OSX_EXTERNAL_PROJECT_ARGS}
       -DCMAKE_INSTALL_PREFIX:PATH=${CMAKE_BINARY_DIR}/Utils

SuperBuild/External_SlicerExecutionModel.cmake

@@ -57,7 +57,7 @@ if(NOT DEFINED ${extProjName}_DIR AND NOT ${USE_SYSTEM_${extProjName}})
     GIT_TAG ${${proj}_GIT_TAG}
     SOURCE_DIR ${proj}
     BINARY_DIR ${proj}-build
-    ${cmakeversion_external_update}
+    ${cmakeversion_external_update} "${cmakeversion_external_update_value}"
     CMAKE_GENERATOR ${gen}
     CMAKE_ARGS
       ${CMAKE_OSX_EXTERNAL_PROJECT_ARGS}

SuperBuild/External_Uncrustify.cmake

@@ -26,7 +26,7 @@ if(NOT DEFINED Uncrustify_EXE AND NOT ${USE_SYSTEM_Uncrustify})
   ExternalProject_add(${proj}
     GIT_REPOSITORY ${Uncrustify_REPOSITORY}
     GIT_TAG ${Uncrustify_GIT_TAG}
-    ${cmakeversion_external_update}
+    ${cmakeversion_external_update} "${cmakeversion_external_update_value}"
     SOURCE_DIR ${proj}
     BINARY_DIR ${proj}-build
     CONFIGURE_COMMAND <SOURCE_DIR>/configure --prefix=${CMAKE_BINARY_DIR}/Utils

SuperBuild/External_VTK.cmake

@@ -150,7 +150,7 @@ if(NOT DEFINED ${extProjName}_DIR AND NOT ${USE_SYSTEM_${extProjName}})
     GIT_TAG ${${proj}_GIT_TAG}
     SOURCE_DIR ${proj}
     BINARY_DIR ${proj}-build
-    ${cmakeversion_external_update}
+    ${cmakeversion_external_update} "${cmakeversion_external_update_value}"
     CMAKE_GENERATOR ${gen}
     CMAKE_ARGS
       ${CMAKE_OSX_EXTERNAL_PROJECT_ARGS}