Fix gstat's interactive f and q commands

[asomers]

Summary

curses and libedit don't play well together. After last year's libedit
upgrade in head, they play even less well together. This change resets some
curses settings after they get screwed up by libedit calls. Without it,
gstat's interactive commands require an extra "enter", screw up the terminal
on exit, and screw up the display if the user enters an invalid filter
string.

PR 204852

Test Plan

Run gstat. Verify that the f command works and that the screen looks
correct after entering an invalid filter string at the f prompt. Use q to
quit, and verify that the terminal still works afterwards.

[pfg]

Yes I had to revert a libedit upgrade affecting lldb.
It is good to less dependent on libedit's weirdness here.

[imp]

<3

And here I thought all this was due to libxo integration...