cmake HAVE_PR_SET_PTRACER examples

oscarlab/betrfs cmake_modules/TokuFeatureDetection.cmake :64 

check_symbol_exists(PR_SET_PTRACER "sys/prctl.h" HAVE_PR_SET_PTRACER)

alibaba/AliSQL storage/tokudb/ft-index/cmake_modules/TokuFeatureDetection.cmake :59 

check_symbol_exists(PR_SET_PTRACER "sys/prctl.h" HAVE_PR_SET_PTRACER)

percona/PerconaFT cmake_modules/TokuFeatureDetection.cmake :60 

check_symbol_exists(PR_SET_PTRACER "sys/prctl.h" HAVE_PR_SET_PTRACER)