cmake HAVE_BACKTRACE_WITHOUT_EXECINFO examples

oscarlab/betrfs cmake_modules/TokuFeatureDetection.cmake :93 

check_function_exists(backtrace HAVE_BACKTRACE_WITHOUT_EXECINFO)

alibaba/AliSQL storage/tokudb/ft-index/cmake_modules/TokuFeatureDetection.cmake :88 

check_function_exists(backtrace HAVE_BACKTRACE_WITHOUT_EXECINFO)

percona/PerconaFT cmake_modules/TokuFeatureDetection.cmake :89 

check_function_exists(backtrace HAVE_BACKTRACE_WITHOUT_EXECINFO)