Fix warning C4164 in MSVC.

Fix: crypto\whrlpool\wp_block.c(90) : warning C4164: '_rotl64' : intrinsic function not declared.
Fixes #9487
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9488)

(cherry picked from commit 0c789f59f117ccbb30ffc621216ba776117c7c61)

crypto/whrlpool/wp_block.c

@@ -87,6 +87,7 @@ typedef unsigned long long u64;
 #ifndef PEDANTIC
 # if defined(_MSC_VER)
 #  if defined(_WIN64)            /* applies to both IA-64 and AMD64 */
+#   include <stdlib.h>
 #   pragma intrinsic(_rotl64)
 #   define ROTATE(a,n) _rotl64((a),n)
 #  endif