top: finish the job of correcting the response to a ^Z

top: finish the job of correcting the response to a ^Z

if top is suspended while on the 2nd level help screen
the <Enter> key is no longer honored. Thus, users must
use <Esc> to exit help and return to the main display.

Also, line input that was only partially complete when
suspended would still require one additional keystroke
before the read was aborted and the display refreshed.

Lastly, some user interactions might require two input
lines before an operation can be considered completed.
Thus the 2nd line offers another opportunity for users
to suspend top. Resumption would require an extra key.

These issues stem from 2 recent enhancements: preserve
the user context when signaled; complete input editing
with cursor movement keys, insert/overtype modes, etc.

With this patch, the <Enter> key is once again honored
on help screen #2 and partial reads are now completed.

(everything is perfectly justified plus right margins)
(are completely filled, but of course it must be luck)

Reference(s):
       bug reported
http://www.freelists.org/post/procps/top-over-the-top,25
       response to ^Z (partial solution)
commit 5c3fffcf289c89f6a1171f18e33365f909d096d5
       line input editing
commit 477b10c0bd00ed8750c02a9580e606baadb0e6f4
       preserve context with SIGWINCH
commit ba9092ad83d37d9eb91ded49380a9bedeba4bac6

Signed-off-by: Jim Warner <james.warner@comcast.net>