internal/zstd: allow zero dictionary id
A value of 0 has same meaning as no Dictionary_ID,
in which case the frame may or may not need a dictionary to be decoded,
and the ID of such a dictionary is not specified.
See https://github.com/facebook/zstd/issues/2172
For #62513
Change-Id: If0eafcbc5d2188576f0cb687234e30c9eb4037a6
GitHub-Last-Rev:
9cf12dcf194a90367a74b808bbe464815f71f42a
GitHub-Pull-Request: golang/go#63268
Reviewed-on: https://go-review.googlesource.com/c/go/+/531515
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>