devel/libblake3: New port: C library providing BLAKE3

C library providing BLAKE3 hash function.

BLAKE3 is a cryptographic hash function that is:

• Much faster than MD5, SHA-1, SHA-2, SHA-3, and BLAKE2.
• Secure, unlike MD5 and SHA-1. And secure against length extension, unlike SHA-2.
• Highly parallelizable across any number of threads and SIMD lanes, because it's a Merkle tree on the inside.
• Capable of verified streaming and incremental updates, again because it's a Merkle tree.
• A PRF, MAC, KDF, and XOF, as well as a regular hash.
• One algorithm with no variants, which is fast on x86-64 and also on smaller architectures.