[fuchsia]: Remove obsolete libvulkan dependencies.

Since MA-488 is closed now, we can remove the dependencies on
libtrace-engine.so and libasync-default.so from libvulkan.so.
This should simplify building packages that depend on the
vulkan loader. See the Chromium bug below for an example.

Bug: 13096, http://crbug.com/1001081
Change-Id: If559427cb408245a5c7671b9175b56159a306c91
diff --git a/BUILD.gn b/BUILD.gn
index 7cef22b..699016a 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -146,26 +146,9 @@
         ":dlopen_fuchsia",
       ]
 
-      # TODO(MA-488) - while these shared libraries are needed by vulkan icd
-      # the app must provide them, so we add the deps here.
-      deps += [ "//zircon/public/lib/trace-engine" ]
-      deps += [ "//zircon/public/lib/async-default" ]
-
       libs = [ "zircon" ]
 
       runtime_deps = [ "//zircon/public/lib/fdio:fdio_sdk" ]
-
-      # TODO(MA-488): remove this too
-      runtime_deps += [ "//zircon/public/lib/trace-engine:trace-engine_sdk" ]
-      runtime_deps += [ "//zircon/public/lib/async-default:async-default_sdk" ]
-
-      # TODO(MA-488): The //zircon/public/lib/async-default dep gives us a dep
-      # on //zircon/public/lib/async, which uses the C++ standard library and
-      # is linked statically (built from source, though async-default is a
-      # prebuilt shared library).  So link in the C++ standard library
-      # statically just to satisfy those references.  When the async-default
-      # dep is dropped, this can change to "none" (i.e. be removed).
-      libcxx_linkage = "static"
     }
   }
 }