[Java] Fixed 32-bit overflowing issue when converting jlong to size_t

Summary:
Fixed 32-bit overflowing issue when converting jlong to size_t by
capping jlong to std::numeric_limits<size_t>::max().

Test Plan:
make rocksdbjava
make jtest

Reviewers: ankgup87, ljin, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23511