Fix spirv-tools include path

Change-Id: I7574c8d99f0e68d753e5714731aec57e0b20f327
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/237799
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
1 file changed