Type annotations for instruction operands are omitted, e.g.
```
%3 = struct $S(%1, %2)
```
Operand types are redundant anyway and were only used for sanity checking in the SIL parser.
But: operand types _are_ printed if the definition of the operand value was not printed yet.
This happens:
* if the block with the definition appears after the block where the operand's instruction is located
* if a block or instruction is printed in isolation, e.g. in a debugger
The old behavior can be restored with `-Xllvm -sil-print-types`.
This option is added to many existing test files which check for operand types in their check-lines.
The main point of this change is to make sure that a shared function always has a body: both, in the optimizer pipeline and in the swiftmodule file.
This is important because the compiler always needs to emit code for a shared function. Shared functions cannot be referenced from outside the module.
In several corner cases we missed to maintain this invariant which resulted in unresolved-symbol linker errors.
As side-effect of this change we can drop the shared_external SIL linkage and the IsSerializable flag, which simplifies the serialization and linkage concept.
We import a C function taking a non-const pointer 'self' parameter
as a mutating method.
The getParameterTypes() helper method in SILGenBridging.cpp would
assert upon encountering the inout 'self' parameter, even though
emitForeignToNativeThunk() would still emit correct code as long
as the 'self' type was not bridged.
Relax the assertion a bit to hopefully still catch bugs where
other parameters are unexpectedly 'inout', but allow it on 'self',
and add a test.
Fixes <rdar://problem/70346482>.
