libgo: Define PtraceRegs for Alpha GNU/Linux.

From Uros Bizjak.

From-SVN: r174502

libgo/syscalls/syscall_linux_alpha.go

@@ -6,6 +6,38 @@
 
 package syscall
 
+type PtraceRegs struct {
+	R0 uint64
+	R1 uint64
+	R2 uint64
+	R3 uint64
+	R4 uint64
+	R5 uint64
+	R6 uint64
+	R7 uint64
+	R8 uint64
+	R19 uint64
+	R20 uint64
+	R21 uint64
+	R22 uint64
+	R23 uint64
+	R24 uint64
+	R25 uint64
+	R26 uint64
+	R27 uint64
+	R28 uint64
+	Hae uint64
+	Trap_a0 uint64
+	Trap_a1 uint64
+	Trap_a2 uint64
+	Ps uint64
+	Pc uint64
+	Gp uint64
+	R16 uint64
+	R17 uint64
+	R18 uint64
+}
+
 func (r *PtraceRegs) PC() uint64 {
 	return r.Pc;
 }