It's almost 2018, Linux 3.17 -- the first kernel with getrandom(2) --
was released in October 2014, and being able to assume getrandom lets
us simplify and improve some security-related code in libc, and revert a
hack to getentropy that's been necessary in the meantime. Only the fugu
kernel doesn't have getrandom(2) at this point, and that's EOL.
Bug: http://b/67014255
Test: ran tests
Change-Id: I1736f4dd33d50fe99e7a524851180989f4c85a33
iOS 10 has <sys/random.h> with getentropy, glibc >= 2.25 has
<sys/random.h> with getentropy and getrandom. (glibc also pollutes
<unistd.h>, but that seems like a bad idea.)
Also, all supported devices now have kernels with the getrandom system
call.
We've had these available internally for a while, but it seems like the
time is ripe to expose them.
Bug: http://b/67014255
Test: ran tests
Change-Id: I76dde1e3a2d0bc82777eea437ac193f96964f138
