Update polkadot-v0.9.29

[OverOrion]

Fixes #1021

[OverOrion]

Currently this is blocked, because a toolchain update is needed for the stabilised then_some used in substrate.
However the toolchain can not be updated as mentioned in #1000.

---

I have checked whether sgx_tstd would have worked with a more recent toolchain version (2022-06-30), but it did not 😞.

error: duplicate diagnostic item found: `CStr`.
   --> incubator-teaclave-sgx-sdk/sgx_trts/src/c_str.rs:206:1
    |
206 | / pub struct CStr {
207 | |     // FIXME: this should not be represented with a DST slice but rather with
208 | |     //        just a raw `c_char` along with some form of marker to make
209 | |     //        this an unsized type. Essentially `sizeof(&CStr)` should be the
210 | |     //        same as `sizeof(&c_char)` but `CStr` should be an unsized type.
211 | |     inner: [c_char],
212 | | }
    | |_^
    |
    = note: the diagnostic item is first defined in crate `core`.

error: duplicate diagnostic item found: `cstring_type`.
   --> incubator-teaclave-sgx-sdk/sgx_trts/src/c_str.rs:124:1
    |
124 | / pub struct CString {
125 | |     // Invariant 1: the slice ends with a zero byte and has a length of at least one.
126 | |     // Invariant 2: the slice contains only one zero byte.
127 | |     // Improper usage of unsafe function can break Invariant 2, but not Invariant 1.
128 | |     inner: Box<[u8]>,
129 | | }
    | |_^
    |
    = note: the diagnostic item is first defined in crate `alloc`.

[OverOrion]

If the clippy lint large_enum_variant should be suppressed let me know and I will drop the patch for it.

[clangenb]

One remark, otherwise it looks good!

[clangenb]

here, we still need to update the branch afterwards

[clangenb]

Nice, looks good to me. I have only one remark!

[clangenb]

If you know some context about the None here, I would prefer an expect. If it is something that never fails in our case, it is even better, and you can write like: expect("fails never because of ....; qed).

If it can fail, I would prefer to actually return a result here.

[OverOrion]

This should not fail as long as now.as_secs() (aka secs) fit into i64. The as keyword will silently convert it into -1 (e.g. when secs == u64::MAX) and that's when it would fail.

Revised in 89e7ac2.

[clangenb]

The great merge has arrived!