[tex-live] Make the extensions for formats different for each engine.

[Fabrice Popineau]

> Right now pdftex uses .fmt for its formats (e.g., latex.fmt) just as
> tex does.  Similar for pdfetex and etex, which both use .efmt.  I
> don't believe this is a desirable situation, and would like to change
> this, possible so that

> Thoughts?

What's the purpose? Ensure that some tex engine won't be called with a
format not created by the same engine? In this case it is not
bulletproof to store the information only in the format file name. Why
not adding a fingerprint inside the format file itself?

Fabrice