xl/16.1.1 with cpp14, openmp build, nightly test failures

[ndellingwood]

Various tests are failing on White with the xl/16.1.1 compiler in an OpenMP build with C++14 enabled.

Sample failure output:

04:37:20 1: /home/jenkins/white/workspace/Kokkos_develop_white_xl_16.1_cpp14/kokkos/core/unit_test/TestMemoryPool.hpp:311: Failure
04:37:20 1: Value of: result
04:37:20 1:   Actual: 62365
04:37:20 1: Expected: nfill
04:37:20 1: Which is: 70000
04:37:20 1: [  FAILED  ] openmp.memory_pool (9 ms)
04:37:20 1: [ RUN      ] openmp.cxx11
04:37:20 1: CXX11 ( test = 'AddTest' FAILED : relative error 0.0486693 > tolerance 1e-14
04:37:20 1: /home/jenkins/white/workspace/Kokkos_develop_white_xl_16.1_cpp14/kokkos/core/unit_test/TestCXX11.hpp:373: Failure
04:37:20 1: Value of: (TestCXX11::Test<TEST_EXECSPACE>(1))
04:37:20 1:   Actual: false
04:37:20 1: Expected: true
04:37:20 1: [  FAILED  ] openmp.cxx11 (0 ms)

  # Reproducer instructions:
  #   Load modules:
        module load cmake/3.12.3 ibm/xl/16.1.1 gcc/7.2.0

  #   Use generate_makefile line below to call cmake which generates makefile for this build:
        <KOKKOS_PATH>/generate_makefile.bash --with-devices=OpenMP --arch=Power8,Kepler37 --compiler=/home/projects/ppc64le/ibm/xlC/16.1.1/bin/xlC --cxxflags="-O3 -Wall -Wshadow -pedantic -Wsign-compare -Wtype-limits -Wuninitialized -qgcc_cpp_stdinc=/home/projects/ppc64le/gcc/7.2.0/include/c++/7.2.0 -I/home/projects/ppc64le/gcc/7.2.0/include/c++/7.2.0/powerpc64le-unknown-linux-gnu" --cxxstandard="14" --ldflags=""  --kokkos-path=<KOKKOS_PATH> --no-examples --with-options=enable_large_mem_tests

If testing on White, I suggest the rhel7T queue as the Kepler queue is down to a single node and tends to be congested.

[crtrott]

This was potentially caused by #2605 too. We had no successful testing since the revert due to wide spread file system issues though. But on a power 9 system I can't reproduce this right now.