fdo#63154 Removed unused solar.h ref. in svx

Change-Id: I1671746d6c433fa3b770eb58bc418e4eddbe8dd4
Reviewed-on: https://gerrit.libreoffice.org/7737
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>