Auto merge of #3477 - RalfJung:win-no-std, r=RalfJung

no_std works on Windows now

Since we now properly support the magic linker section for TLS dtors, the no_std test works on Windows.

Author: bors

tests/fail/panic/no_std.rs

@@ -1,10 +1,6 @@
 #![feature(start, core_intrinsics)]
 #![no_std]
 //@compile-flags: -Cpanic=abort
-// windows tls dtors go through libstd right now, thus this test
-// cannot pass. When windows tls dtors go through the special magic
-// windows linker section, we can run this test on windows again.
-//@ignore-target-windows: no-std not supported on Windows
 
 // Plumbing to let us use `writeln!` to host stderr: