NativeFormatting.cpp - add missing implicit MathExtras.h header dependency. NFCI.

Noticed while investigating if we can remove an unnecessary MathExtras.h include from SmallVector.h

llvm/lib/Support/NativeFormatting.cpp

@@ -11,6 +11,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
 #include <float.h>