gc-pbkdf2-sha1 is deprecated

[Bruce Korb]

Hi Bruno, et al.,

Next question: what do I do about crypto/gc-pbkdf2-sha1? It is labeled 
as "deprecated", but I need a function that produces precisely the same 
result. It really doesn't matter to me that folks have figured out how 
to jigger a file to produce an arbitrary sha1 sum. I only need a fairly 
random result from summing a few tens of bytes of text. So as long as 
"deprecate" doesn't mean it's going away, I'm fine. I use the code to 
create an unguessable password. Just because it's possible to use 
different source text to produce the same password doesn't matter at all. :)

Cheers - Bruce