if-let and when-let: parallel or sequential

[John Mastro]

Hi,

I noticed that the new `if-let' and `when-let' in trunk's subr-x create
their bindings sequentially (like `let*' rather than `let'). Would there
be any interest in renaming these to `if-let*' and `when-let*', and
adding parallel-binding versions under the current names?

It's obviously a tiny matter in the scheme of things, but I do think
it's worth sticking to the existing naming convention given the history
and context.

(If this change would be welcome, and nobody beats me to it, I would be
happy to submit a patch and copyright assignment.)

Thanks

--
John Mastro