Migrate the remaining run-make/coverage-reports tests over to run-coverage

To make it easier to verify that the output snapshots have been migrated
faithfully, this change adds some temporary helper code that lets us avoid
having to completely re-bless the existing snapshots.

A later change in this PR will then re-bless the tests and remove the temporary
helper code.

tests/run-coverage/auxiliary/inline_always_with_dead_code.rs

@@ -0,0 +1,22 @@
+// compile-flags: -Cinstrument-coverage -Ccodegen-units=4 -Copt-level=0
+
+#![allow(dead_code)]
+
+mod foo {
+    #[inline(always)]
+    pub fn called() { }
+
+    fn uncalled() { }
+}
+
+pub mod bar {
+    pub fn call_me() {
+        super::foo::called();
+    }
+}
+
+pub mod baz {
+    pub fn call_me() {
+        super::foo::called();
+    }
+}