[magma] Remove dependency on async-default header

Magma shouldn't link against async-default, so remove the (unused)
include of its header. Also add assert_no_deps to ensure the dependency
isn't added back.

Change-Id: Ide4d37d43dbd17f7d19235509c115af40726d757
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/404860
Commit-Queue: John Bauman <jbauman@google.com>
Reviewed-by: Craig Stout <cstout@google.com>
Testability-Review: Craig Stout <cstout@google.com>
diff --git a/src/graphics/lib/magma/src/libmagma/BUILD.gn b/src/graphics/lib/magma/src/libmagma/BUILD.gn
index 3078016..d60d440 100644
--- a/src/graphics/lib/magma/src/libmagma/BUILD.gn
+++ b/src/graphics/lib/magma/src/libmagma/BUILD.gn
@@ -32,7 +32,10 @@
   }
 
   # Magma ICDs are only allowed to depend on (parts of) libc and libzircon, and no other shared libraries.
-  assert_no_deps = [ "//sdk/lib/fdio" ]
+  assert_no_deps = [
+    "//sdk/lib/fdio",
+    "//zircon/system/ulib/async-default",
+  ]
 }
 
 # This library is complete, so it's usable outside BUILD.gn
diff --git a/src/graphics/lib/magma/src/magma_util/platform/zircon/BUILD.gn b/src/graphics/lib/magma/src/magma_util/platform/zircon/BUILD.gn
index 04d4529..bd3efce 100644
--- a/src/graphics/lib/magma/src/magma_util/platform/zircon/BUILD.gn
+++ b/src/graphics/lib/magma/src/magma_util/platform/zircon/BUILD.gn
@@ -387,7 +387,10 @@
     "//zircon/system/ulib/trace-provider:trace-provider-with-static-engine",
   ]
 
-  assert_no_deps = [ "//sdk/lib/fdio" ]
+  assert_no_deps = [
+    "//sdk/lib/fdio",
+    "//zircon/system/ulib/async-default",
+  ]
 }
 
 source_set("trace_provider_with_fdio") {
diff --git a/src/graphics/lib/magma/src/magma_util/platform/zircon/zircon_platform_trace_provider.h b/src/graphics/lib/magma/src/magma_util/platform/zircon/zircon_platform_trace_provider.h
index fed4e9e..3b72440 100644
--- a/src/graphics/lib/magma/src/magma_util/platform/zircon/zircon_platform_trace_provider.h
+++ b/src/graphics/lib/magma/src/magma_util/platform/zircon/zircon_platform_trace_provider.h
@@ -7,7 +7,6 @@
 
 #if MAGMA_ENABLE_TRACING
 #include <lib/async-loop/cpp/loop.h>
-#include <lib/async-loop/default.h>
 #include <lib/trace-provider/provider.h>
 #endif