Rollup merge of rust-lang#40479 - sezaru:master, r=alexcrichton

Fixes other targets rustlibs installation

When the user select more than one target to generate rustlibs for, rustbuild will only install the host one.

This patch fixes it, more info in rust-lang#39235 (comment)

Author: Ariel Ben-Yehuda

Diff for: src/bootstrap/install.rs

@@ -49,12 +49,17 @@ pub fn install(build: &Build, stage: u32, host: &str) {
         install_sh(&build, "docs", "rust-docs", stage, host, &prefix,
                    &docdir, &libdir, &mandir, &empty_dir);
     }
+
+    for target in build.config.target.iter() {
+        install_sh(&build, "std", "rust-std", stage, target, &prefix,
+                   &docdir, &libdir, &mandir, &empty_dir);
+    }
+
     if build.config.rust_save_analysis {
         install_sh(&build, "analysis", "rust-analysis", stage, host, &prefix,
                    &docdir, &libdir, &mandir, &empty_dir);
     }
-    install_sh(&build, "std", "rust-std", stage, host, &prefix,
-               &docdir, &libdir, &mandir, &empty_dir);
+
     install_sh(&build, "rustc", "rustc", stage, host, &prefix,
                &docdir, &libdir, &mandir, &empty_dir);
     t!(fs::remove_dir_all(&empty_dir));