Fix Ctrl+D after ksh receives SIGWINCH (#208)

src/cmd/ksh93/edit/edit.c: ed_read():
- The loop that handles SIGWINCH assumes sfpkrd will return and
  set errno to EINTR if ksh is sent SIGWINCH. This only occurs
  when select(2) is used to wait for input, so tell sfpkrd to
  use select if possible. This is only done if the last argument
  given to sfpkrd is '2', which should avoid regressions.

src/lib/libast/sfio/sfpkrd.c: sfpkrd():
- Always use select if the last argument is 2. This allows
  sfpkrd() to intercept SIGWINCH when necessary.

Fixes: https://github.com/ksh93/ksh/issues/202

NEWS

@@ -9,6 +9,9 @@ Any uppercase BUG_* names are modernish shell bug IDs.
   did not perform an assignment and yielded the value 0 if 'var' was typeset as
   numeric (integer or float) but had not yet been assigned a value.
 
+- Fixed a bug introduced on 2020-08-19: Ctrl+D would break after an
+  interactive shell received SIGWINCH.
+
 2021-03-05:
 
 - Unbalanced quotes and backticks now correctly produce a syntax error