mbv: add async app, sorta works

mbv/configure

@@ -283,9 +283,11 @@ bootloader_image = build_image(
     linker_script="bootloader/bootloader.ld",
 )
 
-def app_image(app):
+def app_image(app, sources=None):
+    if sources is None:
+        sources = glob.glob(f"./apps/{app}/**/*.cc", recursive=True)
     return build_image(
-            source_set(app, glob.glob(f"./apps/{app}/**/*.cc", recursive=True)),
+            source_set(app, sources),
             linker_script="apps/app.ld",
             dependencies=[hal],
             elf_out=f"{app}.elf",
@@ -299,6 +301,13 @@ all = [
         app_image("helloworld"),
         app_image("timer"),
         app_image("uart"),
+        app_image("async", sources=[
+            "apps/async/async.cc",
+            "apps/async/lock.cc",
+            "apps/async/main.cc",
+            "apps/async/trace.cc",
+            "apps/async/uart.cc",
+            ]),
 ]