use results of include-what-you-use

Change-Id: Ia6ebc21da0dcc134d07e040fc32f94a4928aa17c
Reviewed-on: https://gerrit.libreoffice.org/6560
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>