Remove mirror:: and ArtMethod deps in utils.{h,cc}

The latest chapter in the ongoing saga of attempting to dump a DEX
file without having to start a whole runtime instance.  This episode
finds us removing references to ArtMethod/ArtField/mirror.

One aspect of this change that I would like to call out specfically
is that the utils versions of the "Pretty*" functions all were written
to accept nullptr as an argument.  I have split these functions up as
follows:
1) an instance method, such as PrettyClass that obviously requires
this != nullptr.
2) a static method, that behaves the same way as the util method, but
calls the instance method if p != nullptr.
This requires using a full class qualifier for the static methods,
which isn't exactly beautiful.  I have tried to remove as many cases
as possible where it was clear p != nullptr.

Bug: 22322814
Test: test-art-host
Change-Id: I21adee3614aa697aa580cd1b86b72d9206e1cb24
diff --git a/runtime/gc/reference_processor.cc b/runtime/gc/reference_processor.cc
index 4b8f38d..798ecd3 100644
--- a/runtime/gc/reference_processor.cc
+++ b/runtime/gc/reference_processor.cc
@@ -211,7 +211,7 @@
     } else if (klass->IsPhantomReferenceClass()) {
       phantom_reference_queue_.AtomicEnqueueIfNotEnqueued(self, ref);
     } else {
-      LOG(FATAL) << "Invalid reference type " << PrettyClass(klass) << " " << std::hex
+      LOG(FATAL) << "Invalid reference type " << klass->PrettyClass() << " " << std::hex
                  << klass->GetAccessFlags();
     }
   }