pkg/aflow/action/kernel/build: log build errors

Currently, when the kernel build fails, syz-aflow prints something along
the line of:

failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "36"
 "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=workdir/cache/build/1c6c481ef478edbb8bf3afb9d73e9ff157b1a204"
 "bzImage" "compile_commands.json"]: exit status 2

Which is not particularly helpful, especially because the build
directory gets immediately wiped out and the source directory does not
contain the extracted .config which makes reproduction especially
annoying.

The -s flag makes make "silent", meaning that it only prints errors and
not all successfully built compilation units, which keeps the logs more
concise.

Author: FlorentRevest

pkg/aflow/action/kernel/build.go

@@ -45,9 +45,9 @@ func buildKernel(ctx *aflow.Context, args buildArgs) (buildResult, error) {
 		makeArgs := build.LinuxMakeArgs(target, targets.DefaultLLVMCompiler, targets.DefaultLLVMLinker,
 			"ccache", dir, runtime.NumCPU())
 		compileCommnads := "compile_commands.json"
-		makeArgs = append(makeArgs, path.Base(image), compileCommnads)
-		if _, err := osutil.RunCmd(time.Hour, args.KernelSrc, "make", makeArgs...); err != nil {
-			return aflow.FlowError(err)
+		makeArgs = append(makeArgs, "-s", path.Base(image), compileCommnads)
+		if out, err := osutil.RunCmd(time.Hour, args.KernelSrc, "make", makeArgs...); err != nil {
+			return aflow.FlowError(fmt.Errorf("make failed: %w\n%s", err, out))
 		}
 		// Remove main intermediate build files, we don't need them anymore
 		// and they take lots of space. Keep generated source files.