cmake HAVE_WORKING_FORK examples

InsightSoftwareConsortium/ITK Modules/ThirdParty/MINC/src/libminc/CMakeLists.txt :131 

CHECK_FUNCTION_EXISTS(fork     HAVE_WORKING_FORK)

snl-dakota/dakota src/CMakeLists.txt :178 

add_definitions("-DHAVE_WORKING_FORK")