Chromium MacOS bots are at version 10.10, while the configs were
compiled on 10.13. We now pass the version to the compiler when building
LLVM, which modifies the config files to support the specified version.
In this case, it simply undefines HAVE_FUTIMENS.

Bug: b/152339534
Change-Id: I76d231660e6ee6f087bb67389a0a61abe4673740
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/46549Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>