Fix GCC 9.2 constexpr compile errors in array tests (#344)
Fix GCC 9.2 constexpr compile errors in array tests (#344)

For some reason GCC 9.2 chokes on the subscript operator of
reverse_iterator. Using the (commented out) `-n - 1` expression
instead seems to fix this.
electronicarts/EASTL,electronicarts/EASTL,electronicarts/EASTL