Busybox build error with glibc < 2.25

[Markus Mayer]

Hi Thomas,

My apologies for replying to my own e-mail rather than yours. Somehow
I never received a copy of your email in my inbox. I had to read it
via the web archive. This also means I don't know the message's ID for
me to reply to it directly.

I came up with a solution as well. The difference in my approach is
that I am *PROVIDING* the missing getrandom() system call if glibc
doesn't offer it. Therefore, only if glibc doesn't provide it *AND*
the kernel doesn't provide it would seedrng have to go without the
getrandom() implementation. I think this is the main benefit of my
proposal. It won't make a difference with 2.6 kernels, but if one were
to use, say, kernel 4.1 with glibc 2.24, one would definitely benefit
from being able to use getrandom(), even if glibc doesn't offer it.
It's in the kernel, after all.

I haven't made any tweaks to seedrng directly (outside of handling the
alternate source of getrandom()). There may be some room for
improvement there. So far, my proposal also doesn't address uclibc or
musl-libc.

I'll be sending the patch itself in a new thread shortly to solicit
some feedback. I don't want the submission to get lost in a thread
that started out without any patch attached, so I am not including the
proposed code changes here.

Regards,
-Markus