This header is now pre-built as part of third_party/SPIRV-Headers
It was first added by https://swiftshader-review.googlesource.com/c/SwiftShader/+/43035

Bug: b/150936967
Change-Id: I2931cb6475fd2d99cdc015d1a2e3bd759f9255d6
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/45309Tested-by: Nicolas Capens <nicolascapens@google.com>
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>