Use compiler prefix x86_64-linux-musl (#1443)

Author: justsmth

src/lib.rs

@@ -3510,7 +3510,7 @@ impl Build {
                     "x86_64-unknown-linux-gnu" => self.find_working_gnu_prefix(&[
                         "x86_64-linux-gnu", // rustfmt wrap
                     ]), // explicit None if not found, so caller knows to fall back
-                    "x86_64-unknown-linux-musl" => Some("musl"),
+                    "x86_64-unknown-linux-musl" => Some("x86_64-linux-musl"),
                     "x86_64-unknown-netbsd" => Some("x86_64--netbsd"),
                     _ => None,
                 }