Auto merge of #18938 - nnethercote:bug-1409255, r=SimonSapin

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`.

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---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix https://bugzilla.mozilla.org/show_bug.cgi?id=1409255

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because testing is on the Gecko side.

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1 files changed, 7 insertions, 4 deletions

diff --git a/components/url/lib.rs b/components/url/lib.rs
index aba2989cb18..b7d61273370 100644
--- a/components/url/lib.rs
+++ b/components/url/lib.rs
@@ -7,8 +7,8 @@
 #![crate_name = "servo_url"]
 #![crate_type = "rlib"]
 
-#[macro_use] extern crate heapsize;
-#[macro_use] extern crate heapsize_derive;
+#[macro_use] extern crate malloc_size_of;
+#[macro_use] extern crate malloc_size_of_derive;
 #[macro_use] extern crate serde;
 extern crate servo_rand;
 extern crate url;
@@ -28,8 +28,11 @@ use url::{Url, Position};
 
 pub use url::Host;
 
-#[derive(Clone, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd)]
-pub struct ServoUrl(Arc<Url>);
+#[derive(Clone, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd)]
+pub struct ServoUrl(
+    #[ignore_malloc_size_of = "Arc"]
+    Arc<Url>
+);
 
 impl ServoUrl {
     pub fn from_url(url: Url) -> Self {