Seed the random number generator in Windows with rand_s...

src/platform-win32.cc

Index: src/platform-win32.cc
===================================================================
--- src/platform-win32.cc	(revision 5888)
+++ src/platform-win32.cc	(working copy)
@@ -54,6 +54,11 @@
 #define _WIN32_WINNT 0x501
 #endif
 
+// Required before stdlib.h inclsion for cryptographically strong rand_s.
+#ifndef _CRT_RAND_S
+#define _CRT_RAND_S
+#endif  // _CRT_RAND_S
+
 #include <windows.h>
 
 #include <time.h>  // For LocalOffset() implementation.
@@ -584,11 +589,8 @@
 
 void OS::Setup() {
   // Seed the random number generator.
-  // Convert the current time to a 64-bit integer first, before converting it
-  // to an unsigned. Going directly can cause an overflow and the seed to be
-  // set to all ones. The seed will be identical for different instances that
-  // call this setup code within the same millisecond.
-  uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
+  unsigned int seed;
+  CHECK_EQ(rand_s(&seed), 0);
   srand(static_cast<unsigned int>(seed));
 }