Merge branch 'fix-dl-tls-i586-global_asm' into 'master'

re-add the global_asm macro import for i586

See merge request redox-os/relibc!848

src/header/dl-tls/mod.rs

@@ -5,6 +5,9 @@
 // dropped from src/lib.rs.
 #![warn(warnings, unused_variables)]
 
+#[cfg(target_arch = "x86")]
+use core::arch::global_asm;
+
 use alloc::alloc::alloc;
 use core::{alloc::Layout, ptr};