SHA512/224 and SHA512/256

Support added for these two digests, available only via the EVP interface.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5093)
diff --git a/CHANGES b/CHANGES
index 15b41fd..67f0746 100644
--- a/CHANGES
+++ b/CHANGES
@@ -9,6 +9,9 @@
 
  Changes between 1.1.0f and 1.1.1 [xx XXX xxxx]
 
+  *) Added SHA512/224 and SHA512/256 algorithm support.
+     [Paul Dale]
+
   *) The last traces of Netware support, first removed in 1.1.0, have
      now been removed.
      [Rich Salz]