grepview: Fix search in project root with trailing slash
Summary:
Search in files did not work if you choose to search in the current
project and then append a "/" to the location (e.g.
"/home/user/kdevplatform/").
Reviewers: kfunk, mwolff
Reviewed By: kfunk
Subscribers: kdevelop-devel
Differential Revision: https://phabricator.kde.org/D4774