tslib.h: define flags for ts_sample_mt valid variable
tslib.h: define flags for ts_sample_mt valid variable

The check for (valid != 1) for a sample to ignore should stay supported for
now. The real check becomes !(valid & TSLIB_MT_VALID) and we define
TSLIB_MT_VALID_TOOL for future use too.

Signed-off-by: Martin Kepplinger <07ddf30bcca2a0d3056e54ffbfe155352a6af244@posteo.de>

kergoth/tslib,kergoth/tslib,kergoth/tslib,kergoth/tslib