set rustc dylib on manually constructed rustc command

Signed-off-by: onur-ozkan <work@onurozkan.dev>

src/bootstrap/src/core/builder/cargo.rs

@@ -653,14 +653,18 @@ impl Builder<'_> {
                 // Build proc macros both for the host and the target unless proc-macros are not
                 // supported by the target.
                 if target != compiler.host && cmd_kind != Kind::Check {
-                    let error = command(self.rustc(compiler))
+                    let mut rustc_cmd = command(self.rustc(compiler));
+                    self.add_rustc_lib_path(compiler, &mut rustc_cmd);
+
+                    let error = rustc_cmd
                         .arg("--target")
                         .arg(target.rustc_target_arg())
                         .arg("--print=file-names")
                         .arg("--crate-type=proc-macro")
                         .arg("-")
                         .run_capture(self)
                         .stderr();
+
                     let not_supported = error
                         .lines()
                         .any(|line| line.contains("unsupported crate type `proc-macro`"));