COMP: By default, disable JsonCpp support.

Since JsonCpp library are not available by default, this commit changes
the default value for the SlicerExecutionModel_USE_JSONCPP option. That
way building the project only requires ITK and will ensure that existing
project can still build without explicitly turning the option to OFF.

CMakeLists.txt

@@ -67,7 +67,7 @@ endforeach()
 #-----------------------------------------------------------------------------
 # ParameterSerializer support for ModuleDescriptionParser and GenerateCLP subprojects
 #-----------------------------------------------------------------------------
-option(SlicerExecutionModel_USE_JSONCPP "Enable JSON serialization support for GenerateCLP." ON)
+option(SlicerExecutionModel_USE_JSONCPP "Enable JSON serialization support for GenerateCLP." OFF)
 if(SlicerExecutionModel_USE_JSONCPP)
   find_package(JsonCpp REQUIRED)
   set(GenerateCLP_USE_JSONCPP ON)