Update rustc-ap-syntax to 541.0

[kngwyu]

Resolves #1058
cc: @Xanewok @topecongiro

[Xanewok]

Missing ExprKind::While or should this not process while lets?

[kngwyu]

Good catch 👍, thanks

[topecongiro]

@kngwyu My apologies for annoyance, but could you use 542.0.0, please? I have just released rustfmt 1.4.1 w/ 542.0.0 to fix the build failure in the latest nightly.

[kngwyu]

@topecongiro
Thank you for releasing, I've just updated it.

[Xanewok]

Awesome, thank you 💯 Could you cut a new release with the v542 bump? I'll use that to upgrade Racer and rustfmt to a single version in the RLS.

[kngwyu]

Sure, I just opened #1061

[kngwyu]

@Xanewok
Just published 2.1.24

[Xanewok]

Awesome, thank you!

[jiacai2050]

@kngwyu Thanks. But there are still errors when build from master 7c313b3a142726b66006dae49b0c8d67b2877d70

error[E0425]: cannot find function `type_name` in module `any`
   --> /Users/chenxiang/.cargo/registry/src/mirrors.ustc.edu.cn-12df342d903acd47/rustc-ap-serialize-542.0.0/serialize.rs:852:21
    |
852 |                any::type_name::<S>(),
    |                     ^^^^^^^^^ not found in `any`
help: possible candidates are found in other modules, you can import them into scope
    |
7   | use core::intrinsics::type_name;
    |
7   | use std::intrinsics::type_name;
    |

error[E0425]: cannot find function `type_name` in module `any`
   --> /Users/chenxiang/.cargo/registry/src/mirrors.ustc.edu.cn-12df342d903acd47/rustc-ap-serialize-542.0.0/serialize.rs:854:21
    |
854 |                any::type_name::<T>(),
    |                     ^^^^^^^^^ not found in `any`
help: possible candidates are found in other modules, you can import them into scope
    |
7   | use core::intrinsics::type_name;
    |
7   | use std::intrinsics::type_name;
    |

   Compiling syn v0.15.42
error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0425`.

[kngwyu]

@jiacai2050
You can reproduce it with the latest nightly?

[jiacai2050]

@kngwyu rustc 1.38.0-nightly (4560cb830 2019-07-28) compile fine. Many thanks.