port upstream changes: Add new region updating rule in TRON method
port upstream changes: Add new region updating rule in TRON method

source: https://github.com/cjlin1/liblinear/commit/f4ea7bbc7c176185f8fa05f7d81890ea428f1afa

bwaldvogel/liblinear-java,bwaldvogel/liblinear-java