buzhash* chunker: use window_size not self.window_size

src/borg/chunkers/buzhash.pyx

@@ -247,7 +247,7 @@ cdef class Chunker:
         self.remaining -= min_size
         sum = _buzhash(self.data + self.position, window_size, self.table)
 
-        while self.remaining > self.window_size and (sum & chunk_mask) and not (self.eof and self.remaining <= window_size):
+        while self.remaining > window_size and (sum & chunk_mask) and not (self.eof and self.remaining <= window_size):
             p = self.data + self.position
             stop_at = p + self.remaining - window_size
 

src/borg/chunkers/buzhash64.pyx

@@ -224,7 +224,7 @@ cdef class ChunkerBuzHash64:
         self.remaining -= min_size
         sum = _buzhash64(self.data + self.position, window_size, self.table)
 
-        while self.remaining > self.window_size and (sum & chunk_mask) and not (self.eof and self.remaining <= window_size):
+        while self.remaining > window_size and (sum & chunk_mask) and not (self.eof and self.remaining <= window_size):
             p = self.data + self.position
             stop_at = p + self.remaining - window_size