Log Message:
Update to cscope 15.8a

Changes since 15.7a

 - Allow usage of function keys ctrl-f and ctrl-b even from result pane.
 - More informative display of position in a multi-screenful result set.
 - Handle source files with freaky large numbers of lines.
 - Search for assignment failed to recognize >>= and <<=,
   incorrectly recognized ~=, and was implemented somewhat clumsily.
 - Added vi plugin to read cscope db's
 - Tolerate C++ :: scope operator inside argument lists, too.
 - Bug fixes.