sal_Bool to bool in VCL Timer and minor cleanups

Change-Id: I72e3987af4509239b2e989483b7396512c17e48b
Signed-off-by: Rodolfo Ribeiro Gomes <rodolforg@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/6695
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>