Rollup merge of #145353 - CathalMullan:jemalloc-tools, r=Kobzol

bootstrap: Fix jemalloc 64K page support for aarch64 tools

Resolves #133748

The prior page size fix only targeted the compile build step, not the tools step: #135081

Also note that since `miri` always uses jemalloc, I didn't copy the `builder.config.jemalloc(target)` check to the tools section.

Tested by running `strings` on the compiled `miri` binary to see the LG_PAGE value.

Before:

```
> strings miri | grep '^LG_PAGE'
LG_PAGE 14
```

After:

```
> strings miri | grep '^LG_PAGE'
LG_PAGE 16
```

May also need a separate fix for the standalone miri repository: rust-lang/miri#4514 (likely a change needed in miri-script?)

Author: Zalathar

src/bootstrap/src/core/build_steps/compile.rs

@@ -1352,6 +1352,7 @@ pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetS
 
     // Build jemalloc on AArch64 with support for page sizes up to 64K
     // See: https://github.com/rust-lang/rust/pull/135081
+    // See also the "JEMALLOC_SYS_WITH_LG_PAGE" setting in the tool build step.
     if builder.config.jemalloc(target)
         && target.starts_with("aarch64")
         && env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none()

src/bootstrap/src/core/build_steps/tool.rs

@@ -226,6 +226,14 @@ pub fn prepare_tool_cargo(
     // own copy
     cargo.env("LZMA_API_STATIC", "1");
 
+    // Build jemalloc on AArch64 with support for page sizes up to 64K
+    // See: https://github.com/rust-lang/rust/pull/135081
+    // Note that `miri` always uses jemalloc. As such, there is no checking of the jemalloc build flag.
+    // See also the "JEMALLOC_SYS_WITH_LG_PAGE" setting in the compile build step.
+    if target.starts_with("aarch64") && env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none() {
+        cargo.env("JEMALLOC_SYS_WITH_LG_PAGE", "16");
+    }
+
     // CFG_RELEASE is needed by rustfmt (and possibly other tools) which
     // import rustc-ap-rustc_attr which requires this to be set for the
     // `#[cfg(version(...))]` attribute.