libarchive: Initialize passwd/group lookup result

The "result" argument to functions get(pwu|grg)id_r and get(pw|gr)name_r
does not appear in the signatures provided on older platforms.  We set
the pointer to the result memory in case the function ignores it, thus
ensuring initialization.

Utilities/cmlibarchive/libarchive/archive_read_disk_set_standard_lookup.c

@@ -199,6 +199,7 @@ lookup_uname_helper(struct name_cache *cache, id_t id)
     if (cache->buff == NULL)
         return (NULL);
     for (;;) {
+        result = &pwent; /* Old getpwuid_r ignores last argument.  */
         r = getpwuid_r((uid_t)id, &pwent,
                    cache->buff, cache->buff_size, &result);
         if (r == 0)
@@ -247,6 +248,7 @@ lookup_gname_helper(struct name_cache *cache, id_t id)
     if (cache->buff == NULL)
         return (NULL);
     for (;;) {
+        result = &grent; /* Old getgrgid_r ignores last argument.  */
         r = getgrgid_r((gid_t)id, &grent,
                    cache->buff, cache->buff_size, &result);
         if (r == 0)

Utilities/cmlibarchive/libarchive/archive_write_disk_set_standard_lookup.c

@@ -129,6 +129,7 @@ lookup_gid(void *private_data, const char *gname, gid_t gid)
         int r;
 
         for (;;) {
+            result = &grent; /* Old getgrnam_r ignores last argument.  */
             r = getgrnam_r(gname, &grent, buffer, bufsize, &result);
             if (r == 0)
                 break;
@@ -188,6 +189,7 @@ lookup_uid(void *private_data, const char *uname, uid_t uid)
         int r;
 
         for (;;) {
+            result = &pwent; /* Old getpwnam_r ignores last argument.  */
             r = getpwnam_r(uname, &pwent, buffer, bufsize, &result);
             if (r == 0)
                 break;