The source files for version 3.3.1 that shall be fetched from http://download.documentfoundation.org/libreoffice/src/ are no more there. They were moved to http://download.documentfoundation.org/libreoffice/old/src/ Files from other sources are still valid. Plese correct the ebuild.
I fixed it for future in the 3.4.2.3 and laters. Anyway can't you use gentoo mirror system instead of fetching them from upstream sources?
libreoffice-3.3.1.ebuild was removed from portage.