Switch from `count` to `N` for template due to ambiguity with `std::count`

Recent versions of Clang will flag this use of `count` in namespace
`std` as ambiguous due to the existence of `std::count`. To remove this
problem, we can switch to the commonly used `N` for array sizes.

Bug: http://b/155835175
Test: m with aosp_blueline
Change-Id: I983180b6e2e94dadb095f531e13ea415468ee104
1 file changed