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/net_traits/response.rs

@@ -13,7 +13,7 @@ use std::ascii::AsciiExt;
 use std::sync::{Arc, Mutex};
 
 /// [Response type](https://fetch.spec.whatwg.org/#concept-response-type)
-#[derive(Clone, Debug, Deserialize, HeapSizeOf, PartialEq, Serialize)]
+#[derive(Clone, Debug, Deserialize, MallocSizeOf, PartialEq, Serialize)]
 pub enum ResponseType {
     Basic,
     Cors,
@@ -24,7 +24,7 @@ pub enum ResponseType {
 }
 
 /// [Response termination reason](https://fetch.spec.whatwg.org/#concept-response-termination-reason)
-#[derive(Clone, Copy, Debug, Deserialize, HeapSizeOf, Serialize)]
+#[derive(Clone, Copy, Debug, Deserialize, MallocSizeOf, Serialize)]
 pub enum TerminationReason {
     EndUserAbort,
     Fatal,
@@ -33,7 +33,7 @@ pub enum TerminationReason {
 
 /// The response body can still be pushed to after fetch
 /// This provides a way to store unfinished response bodies
-#[derive(Clone, Debug, HeapSizeOf, PartialEq)]
+#[derive(Clone, Debug, MallocSizeOf, PartialEq)]
 pub enum ResponseBody {
     Empty, // XXXManishearth is this necessary, or is Done(vec![]) enough?
     Receiving(Vec<u8>),
@@ -52,7 +52,7 @@ impl ResponseBody {
 
 
 /// [Cache state](https://fetch.spec.whatwg.org/#concept-response-cache-state)
-#[derive(Clone, Debug, Deserialize, HeapSizeOf, Serialize)]
+#[derive(Clone, Debug, Deserialize, MallocSizeOf, Serialize)]
 pub enum CacheState {
     None,
     Local,
@@ -61,7 +61,7 @@ pub enum CacheState {
 }
 
 /// [Https state](https://fetch.spec.whatwg.org/#concept-response-https-state)
-#[derive(Clone, Copy, Debug, Deserialize, HeapSizeOf, Serialize)]
+#[derive(Clone, Copy, Debug, Deserialize, MallocSizeOf, Serialize)]
 pub enum HttpsState {
     None,
     Deprecated,
@@ -74,31 +74,31 @@ pub enum ResponseMsg {
     Errored,
 }
 
-#[derive(Clone, Deserialize, HeapSizeOf, Serialize)]
+#[derive(Clone, Deserialize, MallocSizeOf, Serialize)]
 pub struct ResponseInit {
     pub url: ServoUrl,
     #[serde(deserialize_with = "::hyper_serde::deserialize",
             serialize_with = "::hyper_serde::serialize")]
-    #[ignore_heap_size_of = "Defined in hyper"]
+    #[ignore_malloc_size_of = "Defined in hyper"]
     pub headers: Headers,
     pub referrer: Option<ServoUrl>,
     pub location_url: Option<Result<ServoUrl, String>>,
 }
 
 /// A [Response](https://fetch.spec.whatwg.org/#concept-response) as defined by the Fetch spec
-#[derive(Clone, Debug, HeapSizeOf)]
+#[derive(Clone, Debug, MallocSizeOf)]
 pub struct Response {
     pub response_type: ResponseType,
     pub termination_reason: Option<TerminationReason>,
     url: Option<ServoUrl>,
     pub url_list: Vec<ServoUrl>,
     /// `None` can be considered a StatusCode of `0`.
-    #[ignore_heap_size_of = "Defined in hyper"]
+    #[ignore_malloc_size_of = "Defined in hyper"]
     pub status: Option<StatusCode>,
     pub raw_status: Option<(u16, Vec<u8>)>,
-    #[ignore_heap_size_of = "Defined in hyper"]
+    #[ignore_malloc_size_of = "Defined in hyper"]
     pub headers: Headers,
-    #[ignore_heap_size_of = "Mutex heap size undefined"]
+    #[ignore_malloc_size_of = "Mutex heap size undefined"]
     pub body: Arc<Mutex<ResponseBody>>,
     pub cache_state: CacheState,
     pub https_state: HttpsState,