dev-util/spirv-headers: Uprev to 1.5.4.2_pre20210526

Required by uprev spirv-tools-2020.6, transitively required by uprev of
vulkan-layers.

BUG=b:195986385
TEST=emerge-$BOARD spirv-headers

Change-Id: Iaaea9beec14f6a9e9294e1ca5596b9f892767b13
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3098398
Tested-by: Chad Versace <chadversary@chromium.org>
Auto-Submit: Chad Versace <chadversary@chromium.org>
Reviewed-by: Chia-I Wu <olv@google.com>
Reviewed-by: Matt Turner <msturner@google.com>
Commit-Queue: Chad Versace <chadversary@chromium.org>
3 files changed