Rollup merge of rust-lang#55378 - Keruspe:bootstrap-linker, r=petroch…

…enkov

rustbuild: use configured linker to build boostrap

Currently, bootstrap uses it to compile everything, but x.py wasn't using it yet to build bootstrap itself.
This fixes the build for systems where the linker isn't called `cc`.

src/bootstrap/bootstrap.py

@@ -632,6 +632,9 @@ def build_bootstrap(self):
             target_features += ["-crt-static"]
         if target_features:
             env["RUSTFLAGS"] += "-C target-feature=" + (",".join(target_features)) + " "
+        target_linker = self.get_toml("linker", build_section)
+        if target_linker is not None:
+            env["RUSTFLAGS"] += "-C linker=" + target_linker + " "
 
         env["PATH"] = os.path.join(self.bin_root(), "bin") + \
             os.pathsep + env["PATH"]