Bindings: Fix starting rewind cache position

Set the starting rewind cache position to the current amount of cells
used instead of 0. Therefore, when a rewind occurs when generation starts
(a match result of NO isn't hit), then the state is preserved and
the KV cache isn't reset.

Signed-off-by: kingbri <8082010+kingbri1@users.noreply.github.com>

Author: kingbri1

bindings/binding.cpp

@@ -880,7 +880,7 @@ const char* InferToReadbackBuffer(
     auto [newTokenId, isEnd] = gen(firstBatch, sampler);
 
     // Extra samplers - Banned strings
-    int rewindPos = 0;
+    int rewindPos = llama_get_kv_cache_used_cells(context);
     int rewindTokenId = 0;
     int tokenCount = 0;
     int rewindTokenCount = 0;