Fix build with VS2008

crypto/rand/rand_win.c(70) : error C2065: 'BCRYPT_USE_SYSTEM_PREFERRED_RNG' : undeclared identifier
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9827)

crypto/rand/rand_win.c

@@ -19,7 +19,8 @@
 
 # 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