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/mirror/object_array-inl.h b/runtime/mirror/object_array-inl.h
index 3c2390b..5fb9459 100644
--- a/runtime/mirror/object_array-inl.h
+++ b/runtime/mirror/object_array-inl.h
@@ -238,8 +238,8 @@
   }
   Runtime::Current()->GetHeap()->WriteBarrierArray(this, dst_pos, count);
   if (UNLIKELY(i != count)) {
-    std::string actualSrcType(PrettyTypeOf(o));
-    std::string dstType(PrettyTypeOf(this));
+    std::string actualSrcType(mirror::Object::PrettyTypeOf(o));
+    std::string dstType(PrettyTypeOf());
     Thread* self = Thread::Current();
     if (throw_exception) {
       self->ThrowNewExceptionF("Ljava/lang/ArrayStoreException;",