cmake HAVE_SIGWAIT examples

arkdb/inception configure.cmake :469 

CHECK_FUNCTION_EXISTS (sigwait HAVE_SIGWAIT)

alibaba/AliSQL configure.cmake :576 

CHECK_FUNCTION_EXISTS (sigwait HAVE_SIGWAIT)

Tokutek/mysql-5.5 configure.cmake :409 

CHECK_FUNCTION_EXISTS (sigwait HAVE_SIGWAIT)