100% cpu on notcurses-input exit on macos

[dankamongmen]

I ran notcurses-input from 3.0.13 on macos 12.7.6, using wezterm on my host and going in over ssh. notcurses-input more or less worked, until i tried to exit with Ctrl+D, at which point it hung, chewing a CPU. it might have begun busylooping prior to hitting Ctrl+D, and i'm not yet sure whether this is repeatable. i hit Ctrl+C shortly (i think immediately) before pressing Ctrl+D, if that has anything to do with it.

[dankamongmen]

it appears to be repeatable, and the Ctrl+C does appear relevant. i was able to exit just fine by pressing "abcde^D" but not "abcde^C^D".

[dankamongmen]

with the fix to #2842, this no longer happens. we were blowing up in the fatal signal handler here the same way, but it led to a lock. it works fine now.