Input reuse on base64 by ThePseudo · Pull Request #8587 · uutils/coreutils

Base64: the function has_padding reads the file and then discards it.
The functions fast_encode and fast_decode re-read the file, providing
significant delay in larger files.
This commit  also reduces the amount of computation done inside the
fast_decode function.
In the next commit there will be the fix for the fast_decode function

Signed-off-by: Andrea Calabrese <andrea.calabrese@amarulasolutions.com>

This is the follow-up commit to the improvement of fast_encode and the
reuse of the read file. What is written there is still valid.

Signed-off-by: Andrea Calabrese <andrea.calabrese@amarulasolutions.com>