This adjusts the standard library test suite to mostly pass on Windows.
The remaining failures are due to various cases:
- memory corruption (`_swift_stdlib_free` in swiftDemangle)
- heap corruption (canGrowUsingRealloc)
- withVAList failure (unresolved)
- unicode handling on the command line
The old SIMD types had a conformance to CustomDebugStringConvertible,
but the new ones do not, causing a source compatibility
regression. Add back a CustomDebugStringConvertible conformance.
Fixes rdar://problem/46746829.
Implements SE-0229.
Also updates simd module types in the Apple SDKs to use the new types, and updates a couple tests to work with the new types and protocols.
A single-field struct with an @_alignment attribute does not
have the same layout as its field.
This caused the runtime to compute incorrect layouts for
generic structs containing SIMD types.
Fixes <rdar://problem/33794343>.
