lang/rust: Update to 1.45.1

[tobik]

Summary

Scheduled to be released on 2020-07-30. As this does not look like
it requires full testing again the plan is to land it on 2020-07-30
too. Note that I bumped consumers again since there was a regression
that might cause miscompilation of some code.

https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1451-2020-07-30
https://blog.rust-lang.org/inside-rust/2020/07/27/1.45.1-prerelease.html
https://github.com/rust-lang/rust/compare/1.45.0...stable

Other port changes:

• Apply the "hard links break env::current_exe()" workaround from rP543251 to lang/rust too

Test Plan

11.3 amd64: ok
11.3 i386: ok
12.1 amd64: ok
12.1 i386: ok
13.0 amd64: ok
13.0 i386: ok

[tobik]

There is going to be a 1.45.2 on Monday (2020-08-03). I'll probably just chase it without creating yet another review.

https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1452-2020-08-03