Extract SHA224/256 from bcm

Change-Id: I953441ccf99321184a5b664cc446551fa5e295b4
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/70947
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: Bob Beck <bbe@google.com>
diff --git a/build.json b/build.json
index 23c0634..2e675d8 100644
--- a/build.json
+++ b/build.json
@@ -303,6 +303,7 @@
             "crypto/rsa_extra/rsa_crypt.c",
             "crypto/rsa_extra/rsa_print.c",
             "crypto/sha/sha1.c",
+            "crypto/sha/sha256.c",
             "crypto/siphash/siphash.c",
             "crypto/slhdsa/fors.c",
             "crypto/slhdsa/merkle.c",