Add basic BLAKE2b-256 support.

Our use-case for this does not require optimisation at the current time,
so a clean C implementation is fine.

Change-Id: I8f29572c33e8dbcc37961c099c71c14aafc8d0a3
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/45164
Reviewed-by: David Benjamin <davidben@google.com>

crypto/CMakeLists.txt

diff --git a/crypto/CMakeLists.txt b/crypto/CMakeLists.txt
index 5d1e13e..cde92b5 100644
--- a/crypto/CMakeLists.txt
+++ b/crypto/CMakeLists.txt
@@ -240,6 +240,7 @@
   bio/printf.c
   bio/socket.c
   bio/socket_helper.c
+  blake2/blake2.c
   bn_extra/bn_asn1.c
   bn_extra/convert.c
   buf/buf.c
@@ -492,8 +493,9 @@
   abi_self_test.cc
   asn1/asn1_test.cc
   base64/base64_test.cc
-  buf/buf_test.cc
   bio/bio_test.cc
+  blake2/blake2_test.cc
+  buf/buf_test.cc
   bytestring/bytestring_test.cc
   chacha/chacha_test.cc
   cipher_extra/aead_test.cc