Compile fix for case where tracing disabled

Change-Id: I4a3d0f8cfb1e1541def815361f876d99715d36a2
diff --git a/services/server/env/fuchsia/pvr_gputrace.cc b/services/server/env/fuchsia/pvr_gputrace.cc
index bef7af5..4ea0133 100644
--- a/services/server/env/fuchsia/pvr_gputrace.cc
+++ b/services/server/env/fuchsia/pvr_gputrace.cc
@@ -39,7 +39,8 @@
 }
 
 #include "platform_trace.h"
-
+#include "magma_util/macros.h"
+#include <zircon/syscalls.h>
 
 /******************************************************************************
  Module In-bound API
@@ -80,7 +81,7 @@
 	PVR_ASSERT(pszWorkType);
 
 	// ui64HWTimestampInOSTime is in ns.
-	uint64_t ticks = ui64HWTimestampInOSTimeNs * zx_ticks_per_second() / 1000000000;
+	uint64_t ATTRIBUTE_UNUSED ticks = ui64HWTimestampInOSTimeNs * zx_ticks_per_second() / 1000000000;
 
 	if (eSwType == PVR_GPUTRACE_SWITCH_TYPE_BEGIN)
 	{