GdbTest::testRunGdbScript: fix test to handle whitespace in debuggee path
Reviewers: KDevelop, apol
Reviewed By: KDevelop, apol
Subscribers: kdevelop-devel
Tags: KDevelop
Differential Revision: https://phabricator.kde.org/D14429
(cherry picked from commit 3e8558130e34af4bd9faab15734d8c9656a856be)