strncpy vs safe_strncpy usage

[Tyrell Keene]

Hello fellow humans,

I was looking to start contributing to busybox where/when I can, so I
was taking a look at some low hanging fruit to get an idea of how things
work/dealing with mailing lists/etc.

I came across the note on the busybox.new site that libbb/ could
probably use some attention, and coming out of a project centered around
security, safe_strncpy() caught my eye when I took a look.

I figured auditing the usage of this function vs the stdlib version
(where appropriate) may be a decent first step, but I wanted to double
check before I got too far into anything. 

If there's anything else anyone might think of that they'd recommend as
a first step, I'm all ears.

Cheers.