Auto merge of #21325 - gterzian:crossbeam_integration, r=SimonSapin,jdm

Replace mpsc with crossbeam-channel

Follow up on https://github.com/servo/servo/pull/19515

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Selecting over multiple channels in `std::sync::mpsc` is not stable and likely never will be:

https://github.com/rust-lang/rust/issues/27800#issuecomment-260136777
> It seems the only thing keeping `mpsc_select` around is Servo.

crossbeam-channel is designed specifically to replace `std::sync::mpsc` and fix many of its shortcomings:
https://github.com/stjepang/rfcs-crossbeam/blob/channel/text/2017-11-09-channel.md

This is to be landed together with https://github.com/servo/ipc-channel/pull/183.

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tests/unit/metrics/Cargo.toml

@@ -11,7 +11,7 @@ doctest = false
 
 [dependencies]
 gfx_traits = {path = "../../../components/gfx_traits"}
-ipc-channel = "0.10"
+ipc-channel = "0.11"
 layout = {path = "../../../components/layout"}
 metrics = {path = "../../../components/metrics"}
 msg = {path = "../../../components/msg"}

tests/unit/profile/Cargo.toml

@@ -10,7 +10,7 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
-ipc-channel = "0.10"
+ipc-channel = "0.11"
 profile = {path = "../../../components/profile"}
 profile_traits = {path = "../../../components/profile_traits"}