Allow variadic functions with cdecl calling convention.

[Mark-Simulacrum]

Fixes #40244.

[rust-highfive]

r? @eddyb

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[Mark-Simulacrum]

cc @retep998

[eddyb]

@bors r+

[bors]

📌 Commit 35dd87f has been approved by eddyb

[Mark-Simulacrum]

@bors r-

This fails on armhf, I think the test just needs to be ignored.

Edit: Specifically, just for myself later:

$ export IMAGE=armhf-gnu
[00:57:20] unexpected errors (from JSON output): [
[00:57:20]     Error {
[00:57:20]         line_num: 11,
[00:57:20]         kind: Some(
[00:57:20]             Error
[00:57:20]         ),
[00:57:20]         msg: "11:1: 13:2: The ABI `\"stdcall\"` is not supported for the current target [E0570]"
[00:57:20]     }
[00:57:20] ]

[Mark-Simulacrum]

Ignored the test on arm; r? @eddyb

[eddyb]

@bors r+

[bors]

📌 Commit bf87e17 has been approved by eddyb