Rollup merge of rust-lang#149306 - RalfJung:bootstra-miri-jemalloc, r=Kobzol

bootstrap: Miri now handles jemalloc like everything else

rust-lang#149252 made Miri work like clippy here, so I think this comment can be removed?

Author: Zalathar

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

@@ -228,9 +228,8 @@ pub fn prepare_tool_cargo(
     // own copy
     cargo.env("LZMA_API_STATIC", "1");
 
-    // 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 env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none() {
+    if builder.config.jemalloc(target) && env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none() {
         // Build jemalloc on AArch64 with support for page sizes up to 64K
         // See: https://github.com/rust-lang/rust/pull/135081
         if target.starts_with("aarch64") {