Make KOKKOS_ALIGN_SIZE a configure-time option

[mhoemmen]

Request by @alanw0 . A user would like to use AVX instructions with explicit SIMD types, with Kokkos::View, with the GCC compiler. This requires that KOKKOS_ALIGN_SIZE be at least 32, for a vector width of 4. However, KOKKOS_ALIGN_SIZE is 64 with the Intel compiler and 16 with all other compilers. Alan would like one of the following:

1. KOKKOS_ALIGN_SIZE should depend only on the SIMD vector width, not on the compiler.
2. Users should be able to set KOKKOS_ALIGN_SIZE as a configure-time option.

[alanw0]

Thanks for lodging this issue Mark. I want to also reference Shreyas @sayerhs, so he can stay updated on this.

[hcedwar]

Resolved in PR #1115
KOKKOS_MEMORY_ALIGNMENT is the single configurable memory alignment parameter.