refactor Builder::cargo, clean deps for cmd!=test

Author: collin5

src/bootstrap/builder.rs

@@ -750,11 +750,10 @@ impl<'a> Builder<'a> {
             }
             let rustdoc = self.rustdoc(compiler.host);
             self.clear_if_dirty(&my_out, &rustdoc);
-        } else {
+        } else if cmd != "test" {
             match mode {
                 Mode::Std => {
                     self.clear_if_dirty(&my_out, &self.rustc(compiler));
-                    self.clear_if_dirty(&my_out, &libstd_stamp);
                 },
                 Mode::Test => {
                     self.clear_if_dirty(&my_out, &libstd_stamp);
@@ -765,9 +764,7 @@ impl<'a> Builder<'a> {
                     self.clear_if_dirty(&my_out, &libtest_stamp);
                 },
                 Mode::Codegen => {
-                    self.clear_if_dirty(&my_out, &self.rustc(compiler));
-                    self.clear_if_dirty(&my_out, &libstd_stamp);
-                    self.clear_if_dirty(&my_out, &libtest_stamp);
+                    self.clear_if_dirty(&my_out, &librustc_stamp);
                 },
                 Mode::ToolBootstrap => { },
                 Mode::ToolStd => {

src/bootstrap/compile.rs

@@ -655,7 +655,6 @@ impl Step for CodegenBackend {
         }
 
         let out_dir = builder.cargo_out(compiler, Mode::Codegen, target);
-        builder.clear_if_dirty(&out_dir, &librustc_stamp(builder, compiler, target));
 
         let mut cargo = builder.cargo(compiler, Mode::Codegen, target, "rustc");
         cargo.arg("--manifest-path")