libcrypto.num: add EVP_enc_null_hmac_sha256 #1926

Job	Run time
check_docs	49s
check_update	1m 13s
check-ansi	2m 42s
address_ub_sanitizer	9m 55s
basic_clang	5m 6s
basic_gcc	4m 57s
enable_non-default_options	4m 39s
full_feat_w_abidiff	3m 39s
fuzz_tests	3m 9s
legacy	3m 44s
memory_sanitizer	19m 20s
minimal	2m 10s
no-deprecated	4m 35s
no-legacy	4m 53s
non-caching	14m 4s
no-shared (ubuntu-latest)	1s
threads_sanitizer	5m 12s
no-shared (macos-latest)	5m 19s
external-test-cf-quiche	3m 52s
external-test-pyca (1.51.0, 3.9)	9m 53s
out-of-source-and-install (ubuntu-latest)	1s
out-of-source-and-install (macos-latest)	7m 50s
external-tests	10m 46s
	2h 7m 49s

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