openssl rehash: exit 0 on warnings, same as c_rehash

Fixes #6083
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/6084)

apps/rehash.c

@@ -126,9 +126,10 @@ static int add_entry(enum Type type, unsigned int hash, const char *filename,
     for (ep = bp->first_entry; ep; ep = ep->next) {
         if (digest && memcmp(digest, ep->digest, evpmdsize) == 0) {
             BIO_printf(bio_err,
-                       "%s: skipping duplicate %s in %s\n", opt_getprog(),
+                       "%s: warning: skipping duplicate %s in %s\n",
+                       opt_getprog(),
                        type == TYPE_CERT ? "certificate" : "CRL", filename);
-            return 1;
+            return 0;
         }
         if (strcmp(filename, ep->filename) == 0) {
             found = ep;
@@ -140,7 +141,7 @@ static int add_entry(enum Type type, unsigned int hash, const char *filename,
     if (ep == NULL) {
         if (bp->num_needed >= MAX_COLLISIONS) {
             BIO_printf(bio_err,
-                       "%s: hash table overflow for %s\n",
+                       "%s: error: hash table overflow for %s\n",
                        opt_getprog(), filename);
             return 1;
         }
@@ -231,7 +232,7 @@ static int do_file(const char *filename, const char *fullpath, enum Hash h)
 
     /* Does it have X.509 data in it? */
     if ((b = BIO_new_file(fullpath, "r")) == NULL) {
-        BIO_printf(bio_err, "%s: skipping %s, cannot open file\n",
+        BIO_printf(bio_err, "%s: error: skipping %s, cannot open file\n",
                    opt_getprog(), filename);
         errs++;
         goto end;
@@ -243,7 +244,7 @@ static int do_file(const char *filename, const char *fullpath, enum Hash h)
 
     if (sk_X509_INFO_num(inf) != 1) {
         BIO_printf(bio_err,
-                   "%s: skipping %s,"
+                   "%s: warning: skipping %s,"
                    "it does not contain exactly one certificate or CRL\n",
                    opt_getprog(), filename);
         /* This is not an error. */