Signal currentDirectoryChanged only check session's background process.

Do not check foreground process to determine if current directory has
changed.  Fixes nasty bugs such as 'man ls' changes to man folder.

This changes the BIC so the patch is different than the one committed
in KDE 4.14.x

Thanks to Arjun AK arjunak234 gmail com

.REVIEW: 120763
.BUG: 305085
.FIXED-IN: 14.12

(cherry picked from commit f269c1ad)