Program/ShaderGL: handle empty info logs The GL driver can sometimes have an empty info log and return an info log length of 0. This would cause a vector to be initialized with a length of 0 just before it's .data() pointer was used, causing a segfault. BUG=angleproject:1323 Change-Id: Iaf9b569ec64a90c714a213562e427fb7cc8daa6b Reviewed-on: https://chromium-review.googlesource.com/330197 Reviewed-by: Zhenyao Mo <zmo@chromium.org> Commit-Queue: Corentin Wallez <cwallez@chromium.org>