crypto/hmac-*: Use 'restrict'. * lib/hmac.h (hmac_md5, hmac_sha1, hmac_sha256, hmac_sha512): Use 'restrict'. * modules/crypto/hmac-md5 (configure.ac): Require AC_C_RESTRICT. * modules/crypto/hmac-sha1 (configure.ac): Likewise. * modules/crypto/hmac-sha256 (configure.ac): Likewise. * modules/crypto/hmac-sha512 (configure.ac): Likewise.