Fix (1 << 31) to (1u << 31) in SkOTTable_OS_2.

include/core/SkTemplates.h

Index: include/core/SkTemplates.h
===================================================================
--- include/core/SkTemplates.h	(revision 13776)
+++ include/core/SkTemplates.h	(working copy)
@@ -11,6 +11,8 @@
 #define SkTemplates_DEFINED
 
 #include "SkTypes.h"
+#include <climits>
+#include <limits>
 #include <new>
 
 /** \file SkTemplates.h
@@ -64,6 +66,15 @@
     );
 }
 
+/** SkTSetBit<N, T>::value is a T with the Nth bit set. */
+template<unsigned N, typename T = uintmax_t> struct SkTSetBit {
+    static const T value = static_cast<T>(1) << N;
+    SK_COMPILE_ASSERT(sizeof(T)*CHAR_BIT > N, SkTSetBit_N_too_large);
+    SK_COMPILE_ASSERT(std::numeric_limits<T>::is_integer, SkTSetBit_T_must_be_integer);
+    SK_COMPILE_ASSERT(!std::numeric_limits<T>::is_signed, SkTSetBit_T_must_be_unsigned);
+    SK_COMPILE_ASSERT(std::numeric_limits<T>::radix == 2, SkTSetBit_T_radix_must_be_2);
+};
+
 /** \class SkAutoTCallVProc
 
     Call a function when this goes out of scope. The template uses two