profile stores empty string values without double quotes

profile stores empty string values without double quotes

        prof_parse.c (need_double_quotes):
        The profile library will happily read in right hand values
        that represent the empty string by parsing "".  However,
        when storing the same empty string back to a file, the
        empty string is written without the double quotes.

        This means that

                [section] foo = ""

        becomes

                [section] foo =

        which is invalid input.  A subsequent attempt to parse the
        profile will result in an invalid input error.

        KFW and KFM's realm editors can inadvertently produce an
        invalid krb5 profile if one of the ignored sections of the
        input profile contains a right hand value that is "".

        This patch was produced by Asanka Herath and it was reviewed
        by jaltman and lxs.

ticket: new
tags: pullup

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@19529 dc483132-0cff-0310-8789-dd5450dbe970