Print new --print option in help.

Author: o01eg

src/librustc_session/config.rs

@@ -913,7 +913,7 @@ pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
             "",
             "print",
             "Compiler information to print on stdout",
-            "[crate-name|file-names|sysroot|cfg|target-list|\
+            "[crate-name|file-names|sysroot|target-libdir|cfg|target-list|\
              target-cpus|target-features|relocation-models|\
              code-models|tls-models|target-spec-json|native-static-libs]",
         ),