pixman-bits-image.c:309:20: runtime error: left shift of 249 by 24 places cannot be represented in type 'int'

Change-Id: I4f67752f7826225cd2175198084a29ac248b873f
Reviewed-on: https://gerrit.libreoffice.org/45226Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>