hmac-*: refactor to remove repetitive code A net removal of 240 lines. * lib/hmac.c: A new parameterized single implementation. * lib/hmac-md5.c: Define parameters and include implementation. * lib/hmac-sha1.c: Likewise. * lib/hmac-sha256.c: Likewise. * lib/hmac-sha512.c: Likewise. * modules/crypto/hmac-md5: Reference the new implementation file. * modules/crypto/hmac-sha1: Likewise. * modules/crypto/hmac-sha256: Likewise. * modules/crypto/hmac-sha512: Likewise. * tests/test-hmac-md5.c: Refactor common code to a single function. * tests/test-hmac-sha1.c: Likewise. * tests/test-hmac-sha256.c: Likewise. * tests/test-hmac-sha512.c: Likewise.