Replace all uses of the heapsize crate with malloc_size_of.

Servo currently uses `heapsize`, but Stylo/Gecko use `malloc_size_of`.
`malloc_size_of` is better -- it handles various cases that `heapsize` does not
-- so this patch changes Servo to use `malloc_size_of`.

This patch makes the following changes to the `malloc_size_of` crate.

- Adds `MallocSizeOf` trait implementations for numerous types, some built-in
  (e.g. `VecDeque`), some external and Servo-only (e.g. `string_cache`).

- Makes `enclosing_size_of_op` optional, because vanilla jemalloc doesn't
  support that operation.

- For `HashSet`/`HashMap`, falls back to a computed estimate when
  `enclosing_size_of_op` isn't available.

- Adds an extern "C" `malloc_size_of` function that does the actual heap
  measurement; this is based on the same functions from the `heapsize` crate.

This patch makes the following changes elsewhere.

- Converts all the uses of `heapsize` to instead use `malloc_size_of`.

- Disables the "heapsize"/"heap_size" feature for the external crates that
  provide it.

- Removes the `HeapSizeOf` implementation from `hashglobe`.

- Adds `ignore` annotations to a few `Rc`/`Arc`, because `malloc_size_of`
  doesn't derive those types, unlike `heapsize`.

components/script/dom/bindings/codegen/CodegenRust.py

@@ -2029,7 +2029,7 @@ def DOMClass(descriptor):
     # padding.
     protoList.extend(['PrototypeList::ID::Last'] * (descriptor.config.maxProtoChainLength - len(protoList)))
     prototypeChainString = ', '.join(protoList)
-    heapSizeOf = 'heap_size_of_raw_self_and_children::<%s>' % descriptor.concreteType
+    mallocSizeOf = 'malloc_size_of_including_raw_self::<%s>' % descriptor.concreteType
     if descriptor.isGlobal():
         globals_ = camel_to_upper_snake(descriptor.name)
     else:
@@ -2038,9 +2038,9 @@ def DOMClass(descriptor):
 DOMClass {
     interface_chain: [ %s ],
     type_id: %s,
-    heap_size_of: %s as unsafe fn(_) -> _,
+    malloc_size_of: %s as unsafe fn(&mut _, _) -> _,
     global: InterfaceObjectMap::%s,
-}""" % (prototypeChainString, DOMClassTypeId(descriptor), heapSizeOf, globals_)
+}""" % (prototypeChainString, DOMClassTypeId(descriptor), mallocSizeOf, globals_)
 
 
 class CGDOMJSClass(CGThing):
@@ -4005,7 +4005,7 @@ class CGEnum(CGThing):
         ident = enum.identifier.name
         decl = """\
 #[repr(usize)]
-#[derive(JSTraceable, PartialEq, Copy, Clone, HeapSizeOf, Debug)]
+#[derive(Copy, Clone, Debug, JSTraceable, MallocSizeOf, PartialEq)]
 pub enum %s {
     %s
 }
@@ -5794,7 +5794,7 @@ def generate_imports(config, cgthings, descriptors, callbacks=None, dictionaries
         'dom::bindings::weakref::WeakReferenceable',
         'dom::windowproxy::WindowProxy',
         'dom::globalscope::GlobalScope',
-        'mem::heap_size_of_raw_self_and_children',
+        'mem::malloc_size_of_including_raw_self',
         'libc',
         'servo_config::prefs::PREFS',
         'std::borrow::ToOwned',