Use the in-tree compiler-builtins

Many of `std`'s dependency have a dependency on the crates.io
`compiler-builtins` when used with the feature
`rustc-std-workspace-core`. Use a Cargo patch to select the in-tree
version instead.

`compiler-builtins` is also added as a dependency of
`rustc-std-workspace-core` so these crates can remove their crates.io
dependency in the future.

library/rustc-std-workspace-core/lib.rs

@@ -2,3 +2,7 @@
 #![no_core]
 
 pub use core::*;
+
+// Crate must be brought into scope so it appears in the crate graph for anything that
+// depends on `rustc-std-workspace-core`.
+use compiler_builtins as _;