Remove KOKKOS_ENABLE_POSIX_MEMALIGN

[masterleinad]

KOKKOS_ENABLE_POSIX_MEMALIGN is only mentioned in

commit 8802c19fdfd492b70288daa8849d0d48f96441eb
Author: crtrott <crtrott@sandia.gov>
Date:   Wed Dec 2 12:27:33 2015 -0700

    Core: Add option KOKKOS_ENABLE_PERFORMANCE_POSIX_MEMALIGN
    This option is off by default, if defined we will use posix
    memalign for HostSpace, but it fails to allocate often.
    This only effects the new view implementation.  

in the whole git history. Hence, it seems to be untested and unused. We should consider removing it (or actually using and testing it).

[dalg24]

Failure (SYCL perf test) is clearly unrelated