If a function body is emitted, all of the declarations inside that function
body must be emitted, too. Previously, lazy var initializers were being skipped
regardless of whether the function containing them was skipped, resulting in
SIL verification errors (which were correctly predicting linker errors).
Resolves rdar://134708502.
The `-experimental-lazy-typecheck` and `-experimental-skip-non-exportable-decls`
flags are not safe to use when emitting a non-resilient module because the
clients of non-resilient modules expect to have access to all the members of a
type in order to e.g. compute the size the type. The
`-experimental-skip-non-exportable-decls` flag skips serialization of
non-public members and would therefore cause mis-compilation. The
`-experimental-lazy-typecheck` is theoretically safe for non-resilient modules
but more requestification work is needed before it can be used successfully.
Resolves rdar://122272758
When `-experimental-skip-non-exportable-decls` is specified, skip emitting
property wrapper backing inits since they cannot be referenced directly by
module clients.
Resolves rdar://119469651
