Fix building binascii when not using the zlib's crc32 (build failure on Windows buildbots)
diff --git a/Modules/binascii.c b/Modules/binascii.c
index 3c27fd6..82c1423 100644
--- a/Modules/binascii.c
+++ b/Modules/binascii.c
@@ -1028,7 +1028,7 @@
 	}
 
 	result = (crc ^ 0xFFFFFFFF);
-	PyBuffer_Release(&pbuf);
+	PyBuffer_Release(&pbin);
 	return PyLong_FromUnsignedLong(result & 0xffffffff);
 }
 #endif  /* USE_ZLIB_CRC32 */