Fix bug for copying winpthread on Windows.

This was broken when I changed this API. ld can't be run from the
arch-specific bin directory because this is missing.

Test: Build, check that winpthread is copied
Bug: None
Change-Id: Ia01e88624b0e66edc5563c931bdfbea174d2a131
diff --git a/ b/
index 96033ec..7c58bd4 100755
--- a/
+++ b/
@@ -165,7 +165,7 @@
     """Installs binutils."""
     check_call(['make', 'install-strip', '-j', str(jobs)])
-    if host in ('win', 'win64'):
+    if host.is_windows:
         arch_install_dir = os.path.join(
             install_dir, ndk.abis.arch_to_triple(arch))
         install_winpthreads(host == 'win', install_dir)