top: fix regression created when fields mgmt reorg'd

top: fix regression created when fields mgmt reorg'd

When the calibrate_fields function was broken up for
mainainability, an obscure regression was introduced.

For the resulting bug to affect the display, all of
the following conditions would have to be met:
 . USE_X_COLHDR was not defined
 . column highlighting had been turned on
 . many, perhaps all, fields were displayable
 . the user then typed the <End> key
 . and the current sort column just happened to
   be immediately to the left of the left-most
   visible field

This patch corrects for that remote possibility.

Reference:
commit d0e16acf156b066d56415b1b7ccbfad4ae1526d8

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