FYI: Kokkos build warnings

[dholladay00]

When compiling kokkos (latest master) with clang 6.0.0 with KOKKOS_ENABLE_COMPILER_WARNINGS=ON, serial execution space only, I get the following warnings:

[ 25%] Building CXX object kokkos/CMakeFiles/kokkos.dir/core/src/impl/Kokkos_Serial_Task.cpp.o
/.../kokkos/core/src/impl/Kokkos_Serial_Task.cpp:63:9: warning: declaration shadows a type
      alias in 'Kokkos::Impl::TaskQueueSpecialization<Kokkos::Serial>' [-Wshadow]
  using execution_space = Kokkos::Serial ;
        ^
/.../kokkos/core/src/impl/Kokkos_Serial_Task.hpp:65:9: note: previous declaration is here
  using execution_space = Kokkos::Serial ;
        ^
/.../kokkos/core/src/impl/Kokkos_Serial_Task.cpp:64:9: warning: declaration shadows a type
      alias in 'Kokkos::Impl::TaskQueueSpecialization<Kokkos::Serial>' [-Wshadow]
  using queue_type      = TaskQueue< execution_space > ;
        ^
/.../kokkos/core/src/impl/Kokkos_Serial_Task.hpp:67:9: note: previous declaration is here
  using queue_type      = Kokkos::Impl::TaskQueue< execution_space > ;
        ^
/.../kokkos/core/src/impl/Kokkos_Serial_Task.cpp:123:9: warning: declaration shadows a type
      alias in 'Kokkos::Impl::TaskQueueSpecialization<Kokkos::Serial>' [-Wshadow]
  using execution_space = Kokkos::Serial ;
        ^
/.../kokkos/core/src/impl/Kokkos_Serial_Task.hpp:65:9: note: previous declaration is here
  using execution_space = Kokkos::Serial ;
        ^
/.../kokkos/core/src/impl/Kokkos_Serial_Task.cpp:124:9: warning: declaration shadows a type
      alias in 'Kokkos::Impl::TaskQueueSpecialization<Kokkos::Serial>' [-Wshadow]
  using queue_type      = TaskQueue< execution_space > ;
        ^
/.../kokkos/core/src/impl/Kokkos_Serial_Task.hpp:67:9: note: previous declaration is here
  using queue_type      = Kokkos::Impl::TaskQueue< execution_space > ;
        ^
4 warnings generated.

This does not have any effect on my use cases (that I know of), just an FYI. Feel free to close.

[crtrott]

Weird that this didn't get caught by our test. We will fix that.

[ndellingwood]

This started showing up in one of the Mayer nightly tests. PR #1795 issued with renamed types to remove the -Wshadow warnings.