Add two trivial fixes from old commits

Reviewed-by: NTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3865)

crypto/objects/obj_dat.pl

@@ -6,6 +6,7 @@
 # in the file LICENSE in the source distribution or at
 # https://www.openssl.org/source/license.html
 
+use integer;
 use strict;
 use warnings;
 

doc/man1/dgst.pod

@@ -21,6 +21,7 @@ B<openssl> B<dgst>
 [B<-verify filename>]
 [B<-prverify filename>]
 [B<-signature filename>]
+[B<-hmac key>]
 [B<-fips-fingerprint>]
 [B<-engine id>]
 [B<-engine_impl>]
@@ -115,6 +116,10 @@ Verify the signature using the private key in "filename".
 
 The actual signature to verify.
 
+=item B<-hmac key>
+
+Create a hashed MAC using "key".
+
 =item B<-mac alg>
 
 Create MAC (keyed Message Authentication Code). The most popular MAC