It's never called externally and for good reason; the only flag to set is
EVP_MD_CTX_FLAG_NO_INIT which is an implementation detail of EVP_PKEY_HMAC
(hopefully to be removed eventually). Indeed, only EVP_PKEY_HMAC ever calls
this function. Except there's no need to because the HMAC_CTX has already been
initialized at that point. (And were it not initialized, that call would not
bode well for the poor HMAC_CTX.)
The legacy EVP_PKEY_HMAC API has test coverage and still works after this
change.
Change-Id: I2fb0bede3c24ad1519f9433f957606de15ba86c7
Reviewed-on: https://boringssl-review.googlesource.com/4970
Reviewed-by: Adam Langley <agl@google.com>
af8731f7a5