Fix typo that I introduced in r357413. Thanks to ensadc@mailnesia.com for the catch.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@357474 91177308-0d34-0410-b5e6-96231b3b80d8

src/chrono.cpp

@@ -195,7 +195,8 @@ steady_clock::now() _NOEXCEPT
 {
   static const LARGE_INTEGER freq = __QueryPerformanceFrequency();
 
-  LARGE_INTEGER counter = __QueryPerformanceFrequency();
+  LARGE_INTEGER counter;
+  (void) QueryPerformanceCounter(&counter);
   return time_point(duration(counter.QuadPart * nano::den / freq.QuadPart));
 }