qemu-tool: do not depend on qemu-timer.c

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/qemu-tool.c b/qemu-tool.c
index 28a4e8d..b46631e 100644
--- a/qemu-tool.c
+++ b/qemu-tool.c
@@ -70,7 +70,7 @@
 
 int64_t cpu_get_clock(void)
 {
-    return qemu_get_clock_ns(rt_clock);
+    return get_clock_realtime();
 }
 
 int64_t cpu_get_icount(void)