tests: Use render target vector's count

We are tracking the render targets in a vector, use
that count rather than maintain another variable.
diff --git a/tests/xgltestframework.cpp b/tests/xgltestframework.cpp
index 01084fa..ee22771 100644
--- a/tests/xgltestframework.cpp
+++ b/tests/xgltestframework.cpp
@@ -400,9 +400,9 @@
 static xgl_testing::Environment *environment;
 
 TestFrameworkXglPresent::TestFrameworkXglPresent() :
-m_device(environment->default_device()),
-m_queue(*m_device.graphics_queues()[0]),
-m_cmdbuf(m_device, xgl_testing::CmdBuffer::create_info(m_device.graphics_queue_node_index_))
+   m_device(environment->default_device()),
+   m_queue(*m_device.graphics_queues()[0]),
+   m_cmdbuf(m_device, xgl_testing::CmdBuffer::create_info(m_device.graphics_queue_node_index_))
 {
     m_quit = false;
     m_pause = false;