cmd/webp-manual-test: blacklist some versions of the dwebp binary.

In particular, the 0.4.0 version of /usr/bin/dwebp that comes with
Ubuntu 14.04 LTS "Trusty", is known to be bad.

As per https://chromium.googlesource.com/webm/libwebp/+/master/NEWS
(grep for 239), versions 0.4.1 and 0.4.2 are also bad.

The alpha_color_cache.webp test file that triggers the discrepancy
between the (correct) Go implementation and the (buggy) libwebp C
implementation was added on 2015-01-23 in
https://chromium.googlesource.com/webm/libwebp-test-data/+/f64fb2da0175fb620540f076a4ba3d310b015a29
in response to https://bugs.chromium.org/p/webp/issues/detail?id=239

Change-Id: Ifee19be0af634b9bf36ff0e16957648e05be840a
Reviewed-on: https://go-review.googlesource.com/18186
Reviewed-by: David Crawshaw <crawshaw@golang.org>
1 file changed