Swift calls the architecture x86_64, OpenBSD calls it amd64. If we use
run_cpu in lit.cfg as-is, then we may need to duplicate lines in each
test for 'x86_64' and 'amd64', which puts a maintenance burden on unit
test developers to ensure they are duplicating changes to each line.
Instead, alias 'amd64' to 'x86_64' for `run_cpu`, but keep the platform
module path referring to 'amd64', in order to distinguish the target
architecture name and the Swift architecture name. This is particularly
relevant for the %target-.*-name pseudovariables used, which should
reference the Swift architecture names.
However, some unit tests are directly referencing %target-cpu directly,
which would break the aliasing. This is done only for swiftinterface
files, so a new substitution is defined in lit.cfg for these variables,
and the affected unit test cases are migrated.
Manually expand out the few places where we had a `not ...` substitution
where the substituted value was invoking `env` to alter the environment.
This pattern is not portable and causes problems when using the
integrated shell, such as on Windows. This was identified during the
LLVM update.
This additionally corrects the use of `not` to indicate that it is
expecting a crashing failure. This was resulting in the Windows tests
failing as `not` was not expecting a crashing failure.
