PE/COFF does not support weak linking semantics. Disable the tests
until we can emulate the required behaviour. This will allow us to
enable running the validation test suite on Windows in the mean time.
Basically the pattern to optimize is:
inject_enum_addr %stackloc, #SomeCase
switch_enum_addr %stackloc ...
This works even if the enum is resilient and the case does not have a payload. As long as we don't have opaque values in SIL we need this peephole to optimize the pattern.
This change fixes the code generation for Float.rounded().
rdar://problem/46353885