update rust

lang/rust/files/patch-src_bootstrap_native.rs

@@ -0,0 +1,34 @@
+There seems to be some kind of race when using llvm-config-wrapper
+for building rust-lld.  Attempt to improve reliability of the build
+by not using it.  llvm-config-wrapper is a hack in the first place
+that is only really needed on Windows.
+
+--- src/bootstrap/native.rs.orig	2020-02-27 18:39:49 UTC
++++ src/bootstrap/native.rs
+@@ -467,25 +467,9 @@ impl Step for Lld {
+         let mut cfg = cmake::Config::new(builder.src.join("src/llvm-project/lld"));
+         configure_cmake(builder, target, &mut cfg, true);
+ 
+-        // This is an awful, awful hack. Discovered when we migrated to using
+-        // clang-cl to compile LLVM/LLD it turns out that LLD, when built out of
+-        // tree, will execute `llvm-config --cmakedir` and then tell CMake about
+-        // that directory for later processing. Unfortunately if this path has
+-        // forward slashes in it (which it basically always does on Windows)
+-        // then CMake will hit a syntax error later on as... something isn't
+-        // escaped it seems?
+-        //
+-        // Instead of attempting to fix this problem in upstream CMake and/or
+-        // LLVM/LLD we just hack around it here. This thin wrapper will take the
+-        // output from llvm-config and replace all instances of `\` with `/` to
+-        // ensure we don't hit the same bugs with escaping. It means that you
+-        // can't build on a system where your paths require `\` on Windows, but
+-        // there's probably a lot of reasons you can't do that other than this.
+-        let llvm_config_shim = env::current_exe().unwrap().with_file_name("llvm-config-wrapper");
+         cfg.out_dir(&out_dir)
+             .profile("Release")
+-            .env("LLVM_CONFIG_REAL", llvm_config)
+-            .define("LLVM_CONFIG_PATH", llvm_config_shim)
++            .define("LLVM_CONFIG_PATH", llvm_config)
+             .define("LLVM_INCLUDE_TESTS", "OFF");
+ 
+         cfg.build();