Enable sccache

Author: Kobzol

src/bootstrap/src/core/build_steps/gcc.rs

@@ -144,23 +144,22 @@ impl Step for Gcc {
             .arg("--disable-bootstrap")
             .arg("--disable-multilib")
             .arg(format!("--prefix={}", install_dir.display()));
-        let cc = builder.build.cc(target).display().to_string();
-        // if let Some(ref ccache) = builder.build.config.ccache {
-        //     cc = format!("{ccache} {cc}");
-        // }
+        let mut cc = builder.build.cc(target).display().to_string();
+        if let Some(ref ccache) = builder.build.config.ccache {
+            cc = format!("{ccache} {cc}");
+        }
         configure_cmd.env("CC", cc);
 
         if let Ok(ref cxx) = builder.build.cxx(target) {
-            let cxx = cxx.display().to_string();
-            // if let Some(ref ccache) = builder.build.config.ccache {
-            //     cxx = format!("{ccache} {cxx}");
-            // }
+            let mut cxx = cxx.display().to_string();
+            if let Some(ref ccache) = builder.build.config.ccache {
+                cxx = format!("{ccache} {cxx}");
+            }
             configure_cmd.env("CXX", cxx);
         }
         configure_cmd.run(builder);
 
         command("make").current_dir(&out_dir).arg(format!("-j{}", builder.jobs())).run(builder);
-        // command("make").current_dir(&out_dir).arg(format!("-j1")).run(builder);
         command("make").current_dir(&out_dir).arg("install").run(builder);
 
         let lib_alias = install_dir.join("lib/libgccjit.so.0");