top: tweak 'Inspect' code for isolated edge situations
If the 'Inspect' feature was used to view a file which
contained binary (unprintable) data, and when the last
line for such a file was purely unprintable, then that
line length would be overstated by the terminal width.
This was also the occasion where valgrind might object
over potential reference to some unitialized value(s).
It was a harmless situation and somewhat rare to begin
with. Anyway this commit will eliminate the potential.
Additionally, supporting readfile logic was simplified
and the 'status line' bytes read is now more accurate.
Signed-off-by: Jim Warner <james.warner@comcast.net>