Capture build artifacts for failed builds

Motivation:
When a build fails, it's desirable to have the build artifacts available
so the build failure can be inspected, investigated and hopefully fixed.

Modification:
Change the Makefile and CI workflow such that the build artifacts are
captured and uploaded when the build fails.

Result:
A "target.zip" file is now available for download on failed GitHub
Actions builds.

.github/workflows/ci-workflow.yml

@@ -43,3 +43,9 @@ jobs:
       # Run the make script
       - name: Make build
         run: make build
+
+      - uses: actions/upload-artifact@v2
+        if: ${{ failure() }}
+        with:
+          name: target
+          path: target/ # or path/to/artifact

Makefile

@@ -17,7 +17,7 @@ clean:
 
 build: image
 	docker create --name build-container netty-incubator-buffer:build
-	docker start -a build-container
+	docker start -a build-container || (docker cp build-container:/home/build/target . && false)
-	docker wait build-container
+	docker wait build-container || (docker cp build-container:/home/build/target . && false)
 	docker cp build-container:/home/build/target .
 	docker rm build-container

src/main/java/io/netty/buffer/api/CompositeBuf.java

@@ -27,8 +27,7 @@ final class CompositeBuf extends RcSupport<Buf, CompositeBuf> implements Buf {
      * non-composite copy of the buffer.
      */
     private static final int MAX_CAPACITY = Integer.MAX_VALUE - 8;
-    private static final Drop<CompositeBuf>
+    private static final Drop<CompositeBuf> COMPOSITE_DROP = new Drop<CompositeBuf>() {
-            COMPOSITE_DROP = new Drop<CompositeBuf>() {
         @Override
         public void drop(CompositeBuf obj) {
             for (Buf buf : obj.bufs) {