Ignore stdout when performing PGO

It is very spammy.

Author: Kobzol

xtask/src/dist.rs

@@ -176,11 +176,14 @@ fn gather_pgo_profile<'a>(
     cmd_gather.run().context("cannot build rust-analyzer with PGO instrumentation")?;
 
     // Run RA on itself to gather profiles
+    eprintln!("Training RA on itself...");
     let train_crate = ".";
     cmd!(
         sh,
         "target/{target}/release/rust-analyzer analysis-stats {train_crate} --run-all-ide-things"
     )
+    // analysis-stats produces an enormous amount of output on stdout
+    .ignore_stdout()
     .run()
     .context("cannot generate PGO profiles")?;