target-alpha: Fix cvtlq.

We were missing the 0xc0000000 mask, leading to incorrect results.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

target-alpha/op_helper.c

@@ -954,7 +954,9 @@ uint64_t helper_cvtqg (uint64_t a)
 
 uint64_t helper_cvtlq (uint64_t a)
 {
-    return (int64_t)((int32_t)((a >> 32) | ((a >> 29) & 0x3FFFFFFF)));
+    int32_t lo = a >> 29;
+    int32_t hi = a >> 32;
+    return (lo & 0x3FFFFFFF) | (hi & 0xc0000000);
 }
 
 static inline uint64_t __helper_cvtql(uint64_t a, int s, int v)