strerror [test $ac_cv_lib_error_at_line = no]
unistd [test $ac_cv_lib_error_at_line = no]
msvc-nothrow [test $ac_cv_lib_error_at_line = no]
strerror [test $ac_cv_lib_error_at_line = no]
unistd [test $ac_cv_lib_error_at_line = no]
msvc-nothrow [test $ac_cv_lib_error_at_line = no]