Fix the block_pcg perf-test when offsets are size_t

[srajama1]

/home/srajama/work_repos/kokkos-kernels/perf_test/sparse/KokkosSparse_block_pcg.cpp(552): error: namespace "std" has no member "cerr"
std::cerr << "PCG is configured with INT, INT, DOUBLE. Test is not compiled as these are not instantiated." << std::endl;
^
/home/srajama/work_repos/kokkos-kernels/perf_test/sparse/KokkosSparse_block_pcg.cpp(552): error: namespace "std" has no member "endl"
std::cerr << "PCG is configured with INT, INT, DOUBLE. Test is not compiled as these are not instantiated." << std::endl;
^
compilation aborted for /home/srajama/work_repos/kokkos-kernels/perf_test/sparse/KokkosSparse_block_pcg.cpp (code 2)
make[2]: *** [KokkosSparse_block_pcg.o] Error 2