[krbdev.mit.edu #7863] profile library mishandles duplicate subsections

[Greg Hudson via RT]

In krb5.conf, if you specify the same top-level section (like [realms]) 
multiple times, you get the same section node each time, because 
parse_std_line calls profile_find_node_subsection before 
profile_add_node.

But when the parser reads a subsection name, it blindly calls 
profile_add_node.  If the subsection already exists, profile_add_node 
creates a second subsection with the same name, which will be invisible 
to searches.