Revert "bootstrap: pass crt-static for the compiler host as well"

This reverts commit ec2b861c2f.

src/bootstrap/builder.rs

@@ -698,10 +698,6 @@ impl<'a> Builder<'a> {
             cargo.env("RUSTC_CRT_STATIC", x.to_string());
         }
 
-        if let Some(x) = self.crt_static(compiler.host) {
-            cargo.env("RUSTC_HOST_CRT_STATIC", x.to_string());
-        }
-
         // Enable usage of unstable features
         cargo.env("RUSTC_BOOTSTRAP", "1");
         self.add_rust_test_threads(&mut cargo);