Merge hwrand.c into rand.c.

By doing this the compiler can notice that much of the code is unused in
the case that we know that we can't have a hardware RNG (i.e. ARM).

Change-Id: I72d364a30080364d700f855640e0164c2c62f0de
Reviewed-on: https://boringssl-review.googlesource.com/6001
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>
4 files changed