Change producer string to have the rustc producer string as prefix

This fixes the comment-section run-make test

Author: bjorn3

scripts/test_rustc_tests.sh

@@ -27,8 +27,6 @@ rm tests/ui/parser/unclosed-delimiter-in-dep.rs # submodule contains //~ERROR
 # missing features
 # ================
 
-rm -r tests/run-make/comment-section # cg_clif doesn't yet write the .comment section
-
 # requires stack unwinding
 # FIXME add needs-unwind to these tests
 rm -r tests/run-make/libtest-junit

src/debuginfo/mod.rs

@@ -20,7 +20,7 @@ use crate::prelude::*;
 
 pub(crate) fn producer() -> String {
     format!(
-        "cg_clif (rustc {}, cranelift {})",
+        "rustc version {} with cranelift {}",
         rustc_interface::util::rustc_version_str().unwrap_or("unknown version"),
         cranelift_codegen::VERSION,
     )