closes bpo-13497: Fix `broken nice` configure test. (GH-12041)


Per POSIX, `nice(3)` requires `unistd.h` and `exit(3)` requires `stdlib.h`.

Fixing the test will prevent false positives with pedantic compilers like clang.
(cherry picked from commit 90c6facebd5666fec85f125ee2795b48b30319a4)

Co-authored-by: ngie-eign <1574099+ngie-eign@users.noreply.github.com>
1 file changed