fdo#63154 Removed unused solar.h ref. in sfx2

Change-Id: I7fd8815482c3491d28e0d353e725e7c37aa52fc3
Reviewed-on: https://gerrit.libreoffice.org/7736
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>