Auto merge of #50336 - japaric:llvm-tools, r=Mark-Simulacrum

ship LLVM tools with the toolchain

this PR adds llvm-{nm,objcopy,objdump,size} to the rustc sysroot (right next to LLD)

this slightly increases the size of the rustc component. I measured these numbers on x86_64 Linux:

- rustc-1.27.0-dev-x86_64-unknown-linux-gnu.tar.gz 180M -> 193M (+7%)
- rustc-1.27.0-dev-x86_64-unknown-linux-gnu.tar.xz 129M -> 137M (+6%)

r? @alexcrichton
cc #49584

src/bootstrap/lib.rs

@@ -199,6 +199,14 @@ use flags::Subcommand;
 use cache::{Interned, INTERNER};
 use toolstate::ToolState;
 
+const LLVM_TOOLS: &[&str] = &[
+    "llvm-nm", // used to inspect binaries; it shows symbol names, their sizes and visibility
+    "llvm-objcopy", // used to transform ELFs into binary format which flashing tools consume
+    "llvm-objdump", // used to disassemble programs
+    "llvm-profdata", // used to inspect and merge files generated by profiles
+    "llvm-size", // prints the size of the linker sections of a program
+];
+
 /// A structure representing a Rust compiler.
 ///
 /// Each compiler has a `stage` that it is associated with and a `host` that
@@ -965,6 +973,27 @@ impl Build {
         self.package_vers(&self.release_num("rustfmt"))
     }
 
+    fn llvm_tools_vers(&self) -> String {
+        // japaric: should we use LLVM version here?
+        // let stdout = build_helper::output(
+        //     Command::new(self.llvm_out(self.config.build).join("build/bin/llvm-size"))
+        //         .arg("--version"),
+        // );
+
+        // for line in stdout.lines() {
+        //     if line.contains("LLVM version") {
+        //         if let Some(vers) = line.split_whitespace().nth(2) {
+        //             return vers.to_string();
+        //         }
+        //     }
+        // }
+
+        // panic!("The output of $LLVM_TOOL has changed; \
+        //         please fix `bootstrap::Build.llvm_tools_vers`");
+
+        self.rust_version()
+    }
+
     /// Returns the `version` string associated with this compiler for Rust
     /// itself.
     ///