Fix unused variable warning in compiler/debug.cpp.

BUG=angle:534

Change-Id: I893e552628c7deba4bc67baae6e5e28b6161c5d4
Reviewed-on: https://chromium-review.googlesource.com/178438
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/compiler/translator/compilerdebug.cpp b/src/compiler/translator/compilerdebug.cpp
index c03867f..10cbe43 100644
--- a/src/compiler/translator/compilerdebug.cpp
+++ b/src/compiler/translator/compilerdebug.cpp
@@ -14,9 +14,9 @@
 #include "compiler/translator/InitializeParseContext.h"
 #include "compiler/translator/ParseContext.h"
 
+#ifdef TRACE_ENABLED
 static const int kTraceBufferLen = 1024;
 
-#ifdef TRACE_ENABLED
 extern "C" {
 void Trace(const char *format, ...) {
     if (!format) return;