Fix build with VS2008
crypto/rand/rand_win.c(70) : error C2065: 'BCRYPT_USE_SYSTEM_PREFERRED_RNG' : undeclared identifier
# include <windows.h>
/* On Windows Vista or higher use BCrypt instead of the legacy CryptoAPI */
-# if defined(_MSC_VER) && defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0600
+# if defined(_MSC_VER) && _MSC_VER > 1500 /* 1500 = Visual Studio 2008 */ \
+ && defined(_WIN32_WINNT) && _WIN32_WINNT >= 0x0600
# define USE_BCRYPTGENRANDOM
# endif
