Skip generating DWARF info for dead code (#3498)

When encountering a subprogram that is dead code (as indicated by the
dead code proposal
https://dwarfstd.org/ShowIssue.php?issue=200609.1), don't generate debug
output for the subprogram or any of its children.

tests/all/debug/testsuite/dead_code.c

@@ -0,0 +1,19 @@
+int bar(int a)
+{
+  int b[50];
+  b[0] = a;
+  b[29] = a;
+  return a;
+}
+
+int baz(int a);
+
+__attribute__((export_name("foo"))) int foo()
+{
+  return baz(10);
+}
+
+__attribute__((noinline)) int baz(int a)
+{
+  return a + 5;
+}

tests/all/debug/translate.rs

@@ -43,6 +43,30 @@ fn check_line_program(wasm_path: &str, directives: &str) -> Result<()> {
     Ok(())
 }
 
+#[test]
+#[ignore]
+#[cfg(all(
+    any(target_os = "linux", target_os = "macos"),
+    target_pointer_width = "64"
+))]
+fn test_debug_dwarf_translate_dead_code() -> Result<()> {
+    check_wasm(
+        "tests/all/debug/testsuite/dead_code.wasm",
+        r##"
+check: DW_TAG_compile_unit
+# We don't have "bar" function because it is dead code
+not:      DW_AT_name	("bar")
+# We have "foo" function
+check: DW_TAG_subprogram
+check:      DW_AT_name	("foo")
+# We have "baz" function
+# it was marked `noinline` so isn't dead code
+check: DW_TAG_subprogram
+check:      DW_AT_name	("baz")
+    "##,
+    )
+}
+
 #[test]
 #[ignore]
 #[cfg(all(