Test basic DWARF generation (#931)

* Add obj generation with debug info
* Add simple transform check

.github/actions/define-dwarfdump-env/main.js

@@ -0,0 +1,11 @@
+#!/usr/bin/env node
+
+// On OSX pointing to brew's LLVM location.
+if (process.platform == 'darwin') {
+  console.log("::set-env name=DWARFDUMP::/usr/local/opt/llvm/bin/llvm-dwarfdump");
+}
+
+// On Linux pointing to specific version
+if (process.platform == 'linux') {
+  console.log("::set-env name=DWARFDUMP::/usr/bin/llvm-dwarfdump-9");
+}