Do not construct out-of-bound pointers in SHA512/SHA1/RIPEMD160 code

src/crypto/ripemd160.cpp

@@ -256,7 +256,7 @@ CRIPEMD160& CRIPEMD160::Write(const unsigned char* data, size_t len)
         ripemd160::Transform(s, buf);
         bufsize = 0;
     }
-    while (end >= data + 64) {
+    while (end - data >= 64) {
         // Process full chunks directly from the source.
         ripemd160::Transform(s, data);
         bytes += 64;