Update Kokkos library in LAMMPS to v2.8.00

# Change Log

## [2.8.00](https://github.com/kokkos/kokkos/tree/2.8.00) (2019-02-05)

[Full Changelog](https://github.com/kokkos/kokkos/compare/2.7.24...2.8.00)

**Implemented enhancements:**

- Capability, Tests: C++14 support and testing [\#1914](https://github.com/kokkos/kokkos/issues/1914)

- Capability: Add environment variables for all command line arguments [\#1798](https://github.com/kokkos/kokkos/issues/1798)

- Capability: --kokkos-ndevices not working for Slurm [\#1920](https://github.com/kokkos/kokkos/issues/1920)

- View: Undefined behavior when deep copying from and to an empty unmanaged view [\#1967](https://github.com/kokkos/kokkos/issues/1967)

- BuildSystem: nvcc\_wrapper should stop immediately if nvcc is not in PATH [\#1861](https://github.com/kokkos/kokkos/issues/1861)

**Fixed bugs:**

- Cuda: Fix Volta Issues 1 Non-deterministic behavior on Volta, runs fine on Pascal [\#1949](https://github.com/kokkos/kokkos/issues/1949)

- Cuda: Fix Volta Issues 2 CUDA Team Scan gives wrong values on Volta with -G compile flag [\#1942](https://github.com/kokkos/kokkos/issues/1942)

- Cuda: illegal warp sync in parallel\_reduce by functor on Turing 75 [\#1958](https://github.com/kokkos/kokkos/issues/1958)

- Threads: Pthreads backend does not handle RangePolicy with offset correctly [\#1976](https://github.com/kokkos/kokkos/issues/1976)

- Atomics: atomic\_fetch\_oper has no case for Kokkos::complex\<double\> or other 16-byte types [\#1951](https://github.com/kokkos/kokkos/issues/1951)

- MDRangePolicy: Fix zero-length range [\#1948](https://github.com/kokkos/kokkos/issues/1948)

- TeamThreadRange: TeamThreadRange MaxLoc reduce doesnt compile  [\#1909](https://github.com/kokkos/kokkos/issues/1909)

## [2.7.24](https://github.com/kokkos/kokkos/tree/2.7.24) (2018-11-04)

[Full Changelog](https://github.com/kokkos/kokkos/compare/2.7.00...2.7.24)

    WorkRange range( self.m_policy , exec.pool_rank() , exec.pool_size() );

    exec.set_work_range(0,range.end()-range.begin(),self.m_policy.chunk_size());

    exec.set_work_range(range.begin()-self.m_policy.begin(),range.end()-self.m_policy.begin(),self.m_policy.chunk_size());

    exec.reset_steal_target();

    exec.barrier();

    long work_index = exec.get_work_index();

    while(work_index != -1) {

      const Member begin = static_cast<Member>(work_index) * self.m_policy.chunk_size()+range.begin();

      const Member begin = static_cast<Member>(work_index) * self.m_policy.chunk_size()+self.m_policy.begin();

      const Member end = begin + self.m_policy.chunk_size() < self.m_policy.end()?begin+self.m_policy.chunk_size():self.m_policy.end();

      ParallelFor::template exec_range< WorkTag >

        ( self.m_functor , begin , end );

      work_index = exec.get_work_index();

    const ParallelReduce & self = * ((const ParallelReduce *) arg );

    const WorkRange range( self.m_policy, exec.pool_rank(), exec.pool_size() );

    exec.set_work_range(0,range.end()-range.begin(),self.m_policy.chunk_size());

    exec.set_work_range(range.begin()-self.m_policy.begin(),range.end()-self.m_policy.begin(),self.m_policy.chunk_size());

    exec.reset_steal_target();

    exec.barrier();

    long work_index = exec.get_work_index();

    reference_type update = ValueInit::init( ReducerConditional::select(self.m_functor , self.m_reducer) , exec.reduce_memory() );

    while(work_index != -1) {

      const Member begin = static_cast<Member>(work_index) * self.m_policy.chunk_size() + range.begin();

      const Member begin = static_cast<Member>(work_index) * self.m_policy.chunk_size() + self.m_policy.begin();

      const Member end = begin + self.m_policy.chunk_size() < self.m_policy.end()?begin+self.m_policy.chunk_size():self.m_policy.end();

      ParallelReduce::template exec_range< WorkTag >

        ( self.m_functor , begin , end

tag:  2.6.00     date: 03:07:2018    master: 62e760fa    develop: d1ba7d71

tag:  2.7.00     date: 05:24:2018    master: e01945d0    develop: 2d13f608

tag:  2.7.24     date: 11:04:2018    master: d3a94192    develop: 7a06fc81

tag:  2.8.00     date: 02:05:2019    master: 34931a36    develop: d1659d1d