We have to use EVP in FIPS mode so we can only partially mitigate timing differences. Make an extra call to HMAC_Update to hash additonal blocks to cover any timing differences caused by removal of padding.
(cherry picked from commit 014265eb02e26f35c8db58e2ccbf100b0b2f0072) (cherry picked from commit 7721c53e5e9fe4c90be420d7613559935a96a4fb)