Update dbg macro test to use check-run-results flag for run-pass test

Updates the dbg-macro-expected behavior test to remove the workaround and use the `check-run-result` flag/feature in compiletest. This serves to test the feature on a real use-case (as mentioned in rust-lang#63751)

Author: nathanwhit

src/test/ui/rfc-2361-dbg-macro/dbg-macro-expected-behavior.rs

@@ -1,7 +1,5 @@
 // run-pass
-// ignore-cloudabi no processes
-// ignore-emscripten no processes
-// ignore-sgx no processes
+// check-run-results
 
 // Tests ensuring that `dbg!(expr)` has the expected run-time behavior.
 // as well as some compile time properties we expect.
@@ -18,7 +16,7 @@ struct Point<T> {
 #[derive(Debug, PartialEq)]
 struct NoCopy(usize);
 
-fn test() {
+fn main() {
     let a: Unit = dbg!(Unit);
     let _: Unit = dbg!(a);
     // We can move `a` because it's Copy.
@@ -67,81 +65,3 @@ fn test() {
     assert_eq!((1u8, 2u32, "Yeah"), dbg!(1u8, 2u32,
                                          "Yeah",));
 }
-
-fn validate_stderr(stderr: Vec<String>) {
-    assert_eq!(stderr, &[
-        ":22] Unit = Unit",
-
-        ":23] a = Unit",
-
-        ":29] Point{x: 42, y: 24,} = Point {",
-        "    x: 42,",
-        "    y: 24,",
-        "}",
-
-        ":30] b = Point {",
-        "    x: 42,",
-        "    y: 24,",
-        "}",
-
-        ":38]",
-
-        ":42] &a = NoCopy(",
-        "    1337,",
-        ")",
-
-        ":42] dbg!(& a) = NoCopy(",
-        "    1337,",
-        ")",
-        ":47] f(&42) = 42",
-
-        "before",
-        ":52] { foo += 1; eprintln!(\"before\"); 7331 } = 7331",
-
-        ":60] (\"Yeah\",) = (",
-        "    \"Yeah\",",
-        ")",
-
-        ":63] 1 = 1",
-        ":63] 2 = 2",
-
-        ":67] 1u8 = 1",
-        ":67] 2u32 = 2",
-        ":67] \"Yeah\" = \"Yeah\"",
-    ]);
-}
-
-fn main() {
-    // The following is a hack to deal with compiletest's inability
-    // to check the output (to stdout) of run-pass tests.
-    use std::env;
-    use std::process::Command;
-
-    let mut args = env::args();
-    let prog = args.next().unwrap();
-    let child = args.next();
-    if let Some("child") = child.as_ref().map(|s| &**s) {
-        // Only run the test if we've been spawned as 'child'
-        test()
-    } else {
-        // This essentially spawns as 'child' to run the tests
-        // and then it collects output of stderr and checks the output
-        // against what we expect.
-        let out = Command::new(&prog).arg("child").output().unwrap();
-        assert!(out.status.success());
-        assert!(out.stdout.is_empty());
-
-        let stderr = String::from_utf8(out.stderr).unwrap();
-        let stderr = stderr.lines().map(|mut s| {
-            if s.starts_with("[") {
-                // Strip `[` and file path:
-                s = s.trim_start_matches("[");
-                assert!(s.starts_with(file!()));
-                s = s.trim_start_matches(file!());
-            }
-            s.to_owned()
-        }).collect();
-
-        validate_stderr(stderr);
-    }
-}

src/test/ui/rfc-2361-dbg-macro/dbg-macro-expected-behavior.run.stderr

@@ -0,0 +1,28 @@
+[$DIR/dbg-macro-expected-behavior.rs:20] Unit = Unit
+[$DIR/dbg-macro-expected-behavior.rs:21] a = Unit
+[$DIR/dbg-macro-expected-behavior.rs:27] Point{x: 42, y: 24,} = Point {
+    x: 42,
+    y: 24,
+}
+[$DIR/dbg-macro-expected-behavior.rs:28] b = Point {
+    x: 42,
+    y: 24,
+}
+[$DIR/dbg-macro-expected-behavior.rs:36]
+[$DIR/dbg-macro-expected-behavior.rs:40] &a = NoCopy(
+    1337,
+)
+[$DIR/dbg-macro-expected-behavior.rs:40] dbg!(& a) = NoCopy(
+    1337,
+)
+[$DIR/dbg-macro-expected-behavior.rs:45] f(&42) = 42
+before
+[$DIR/dbg-macro-expected-behavior.rs:50] { foo += 1; eprintln!("before"); 7331 } = 7331
+[$DIR/dbg-macro-expected-behavior.rs:58] ("Yeah",) = (
+    "Yeah",
+)
+[$DIR/dbg-macro-expected-behavior.rs:61] 1 = 1
+[$DIR/dbg-macro-expected-behavior.rs:61] 2 = 2
+[$DIR/dbg-macro-expected-behavior.rs:65] 1u8 = 1
+[$DIR/dbg-macro-expected-behavior.rs:65] 2u32 = 2
+[$DIR/dbg-macro-expected-behavior.rs:65] "Yeah" = "Yeah"