[compiler-rt] [TSan] leave BufferedStackTrace uninit

Otherwise we have to memset 2040 bytes (255 * 8) for each call

Pull Request: llvm#102255

Author: fmayer

compiler-rt/lib/tsan/dd/dd_rtl.cpp

@@ -19,7 +19,7 @@ namespace __dsan {
 static Context *ctx;
 
 static u32 CurrentStackTrace(Thread *thr, uptr skip) {
-  BufferedStackTrace stack;
+  UNINITIALIZED BufferedStackTrace stack;
   thr->ignore_interceptors = true;
   stack.Unwind(1000, 0, 0, 0, 0, 0, false);
   thr->ignore_interceptors = false;