parsers: fix width of datalen variable in fm1readmarkers Because parsers.c does not define PY_SSIZE_T_CLEAN, "s#" format requires (const char*, int), not (const char*, Py_ssize_t). https://docs.python.org/2/c-api/arg.html This error had no problem before 042344313939, where datalen wasn't used. But now fm1readmarkers() fails with "overflow in obsstore" on Python 2.6.9 (amd64) because upper bits of datalen seem to be filled with 1, making it a negative integer. This problem seems not visible on our Python 2.7 environment because upper bits happen to be filled with 0.