Switch slirp to 3-clause BSD license. This change went in upstream to QEMU's
version of slirp (where this code comes from), with the following checkin:

commit 2f5f89963186d42a7ded253bc6cf5b32abb45cec
Author: aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>
Date:   Mon Jan 26 19:37:41 2009 +0000

    Remove the advertising clause from the slirp license

    According to the FSF, the 4-clause BSD license, which slirp is covered under,
    is not compatible with the GPL or LGPL[1].

    [1] http://www.fsf.org/licensing/licenses/index_html#GPLIncompatibleLicenses

    There are three declared copyright holders in slirp that use the 4-clause
    BSD license, the Regents of UC Berkley, Danny Gasparovski, and Kelly Price.
    Below are the appropriate permissions to remove the advertise clause from slirp
    from each party.

    Special thanks go to Richard Fontana from Red Hat for contacting all of the
    necessary authors to resolve this issue!

    Regents of UC Berkley:
    From ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change

    July 22, 1999

    To All Licensees, Distributors of Any Version of BSD:

    As you know, certain of the Berkeley Software Distribution ("BSD") source
    code files require that further distributions of products containing all or
    portions of the software, acknowledge within their advertising materials
    that such products contain software developed by UC Berkeley and its
    contributors.

    Specifically, the provision reads:

    "     * 3. All advertising materials mentioning features or use of this software
          *    must display the following acknowledgement:
          *    This product includes software developed by the University of
          *    California, Berkeley and its contributors."

    Effective immediately, licensees and distributors are no longer required to
    include the acknowledgement within advertising materials.  Accordingly, the
    foregoing paragraph of those BSD Unix files containing it is hereby deleted
    in its entirety.

    William Hoskins
    Director, Office of Technology Licensing
    University of California, Berkeley

    Danny Gasparovski:

    Subject: RE: Slirp license
    Date: Thu, 8 Jan 2009 10:51:00 +1100
    From: "Gasparovski, Daniel" <Daniel.Gasparovski@ato.gov.au>
    To: "Richard Fontana" <rfontana@redhat.com>

    Hi Richard,

    I have no objection to having Slirp code in QEMU be licensed under the
    3-clause BSD license.

    Thanks for taking the effort to consult me about this.


    Dan ...

    Kelly Price:

    Date: Thu, 8 Jan 2009 19:38:56 -0500
    From: "Kelly Price" <strredwolf@gmail.com>
    To: "Richard Fontana" <rfontana@redhat.com>
    Subject: Re: Slirp license

    Thanks for contacting me, Richard.  I'm glad you were able to find
    Dan, as I've been "keeping the light on" for Slirp.  I have no use for
    it now, and I have little time for it (now holding onto Keenspot's
    Comic Genesis and having a regular US state government position). If
    Dan would like to return to the project, I'd love to give it back to
    him.

    As for copyright, I don't own all of it.  Dan does, so I will defer to
    him.  Any of my patches I will gladly license to the 3-part BSD
    license.  My interest in re-licensing was because we didn't have ready
    info to contact Dan.  If Dan would like to port Slirp back out of
    QEMU, a lot of us 64-bit users would be grateful.

    Feel free to share this email address with Dan.  I will be glad to
    effect a transfer of the project to him and Mr. Bellard of the QEMU
    project.

    Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


    git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6451 c046a42c-6fe2-441c-8c8c-71466251a162