kf5backend.cxx: Use 'free()' instead of 'delete'

'strdup' doc [1] mentions:
"The returned pointer must be passed to 'free' to avoid a memory leak."

This silences a "Mismatched free() / delete / delete []" error that
valgrind outputs.

[1] https://en.cppreference.com/w/c/experimental/dynamic/strdup

Change-Id: I28877be762256a7b995c09415a8ad9977b7998c4
Reviewed-on: https://gerrit.libreoffice.org/77974
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

0 files changed, 0 insertions, 0 deletions