bpo-31629: Add support.SaveSignals (#4183) (#4188)

test_curses now saves/restores signals. On FreeBSD, the curses module
sets handlers of some signals, but don't restore old handlers when
the module is deinitialized.

(cherry picked from commit 19f68301a1295a9c30d9f28b8f1479cdcccd75aa)
2 files changed