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/builder.rs

@@ -453,6 +453,7 @@ impl<'a> Builder<'a> {
                 dist::Cargo,
                 dist::Rls,
                 dist::Rustfmt,
+                dist::LlvmTools,
                 dist::Extended,
                 dist::HashSign
             ),