msvc: Fix TLS destructors

Just like the original article our Windows TLS support is based on predicted,
this symbol must be linked in on MSVC to pull in the necessary support for TLS
variables. This commit fixes a number of unit tests which require that TLS
destructors are run.

src/libstd/lib.rs

@@ -151,6 +151,7 @@
 #![cfg_attr(windows, feature(str_utf16))]
 #![cfg_attr(test, feature(float_from_str_radix, range_inclusive, float_extras))]
 #![cfg_attr(test, feature(test, rustc_private, float_consts))]
+#![cfg_attr(target_env = "msvc", feature(link_args))]
 
 // Don't link to std. We are std.
 #![no_std]