target-alpha: Enable NPTL.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/configure b/configure
index e2dadb0..172b7cf 100755
--- a/configure
+++ b/configure
@@ -2432,6 +2432,7 @@
   ;;
   alpha)
     target_phys_bits=64
+    target_nptl="yes"
   ;;
   arm|armeb)
     TARGET_ARCH=arm