AlarmManagerService.setKernelTime: fix incorrect limit.

There is no TIME_T_MAX, so someone wrote INT_MAX instead. Use
std::numeric_limits<time_t>::max() so we can get the right answer on
both 32-bit and 64-bit systems.

Bug: http://b/156317457
Test: treehugger
Change-Id: I19fdee8601f8b59c4ee0959d59be946bfab6e4d0