spirv-headers: update spirv-tools and shaderc dependency

spirv-headers changed version number convention.
Update spirv-tools and shaderc to remove explicit version dependency
to match the new convention when we will update spirv-headers.

BUG=None
TEST=emerge-volteer spirv-tools
     emerge-volteer shaderc

Change-Id: I12e721c899cc458d3eba550b5e83d4ccf5f84492
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3378582
Tested-by: Romaric Jodin <rjodin@chromium.org>
Reviewed-by: Matt Turner <msturner@google.com>
Commit-Queue: Romaric Jodin <rjodin@chromium.org>
2 files changed