Subzero requires specifying the target CPU features at construction,
and doesn't use this legacy LLVM support code.

It is conceivable that this code was putting build host specific
information into static variables, thus not producing the same binary
when built on different machines.

Bug: chromium:937268
Bug: b/155971541
Change-Id: I8934c4abfebc3901ef50edfe86a0122b1b50e319
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/46689Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>