SF: Fix initialization error when starting a traces

Make sure mWhere is always initialized

Test: start and stop sf trace

Fixes: 128851228
Change-Id: I82b8d195a33a50ad28a78392372b7e72479ef9f8
diff --git a/services/surfaceflinger/SurfaceTracing.cpp b/services/surfaceflinger/SurfaceTracing.cpp
index f1c4347..db78f1d 100644
--- a/services/surfaceflinger/SurfaceTracing.cpp
+++ b/services/surfaceflinger/SurfaceTracing.cpp
@@ -60,7 +60,7 @@
 
 void SurfaceTracing::notify(const char* where) {
     std::lock_guard<std::mutex> sfLock(mFlinger.mDrawingStateLock);
-    mWhere = strdup(where);
+    mWhere = where;
     mConditionalVariable.notify_one();
 }