makeRustPlatform: add rustLibSrc

rust-analyzer: rustcSrc -> rustLibSrc to fix build

pkgs/development/compilers/rust/make-rust-platform.nix

···
   rustcSrc = callPackage ./rust-src.nix {
     inherit rustc;
   };
+
+  rustLibSrc = callPackage ./rust-lib-src.nix {
+    inherit rustc;
+  };
 }

pkgs/development/compilers/rust/rust-lib-src.nix

···
+{ stdenv, rustc }:
+
+stdenv.mkDerivation {
+  name = "rust-lib-src";
+  src = rustc.src;
+  phases = [ "unpackPhase" "installPhase" ];
+
+  installPhase = ''
+    mv library $out
+  '';
+}

pkgs/development/tools/rust/rust-analyzer/generic.nix

···
 
   inherit doCheck;
   preCheck = lib.optionalString doCheck ''
-    export RUST_SRC_PATH=${rustPlatform.rustcSrc}
+    export RUST_SRC_PATH=${rustPlatform.rustLibSrc}
   '';
 
   doInstallCheck = true;

pkgs/development/tools/rust/rust-analyzer/wrapper.nix

···
   unwrapped,
   pname ? "rust-analyzer",
   version ? unwrapped.version,
-  rustcSrc ? rustPlatform.rustcSrc,
+  # Use name from `RUST_SRC_PATH`
+  rustSrc ? rustPlatform.rustLibSrc,
 }: runCommandNoCC "${pname}-${version}" {
   inherit pname version;
   inherit (unwrapped) src meta;
···
 } ''
   mkdir -p $out/bin
   makeWrapper ${unwrapped}/bin/rust-analyzer $out/bin/rust-analyzer \
-    --set-default RUST_SRC_PATH "${rustcSrc}"
+    --set-default RUST_SRC_PATH "${rustSrc}"
 '')