Amends b009aca38a.
The PR predated the introduction of unused variable/constant checks,
thus the build checks weren't reporting this failure until later when
merged into master.
This is for consistency with the documentation on sentinel-terminated
{arrays,slices,pointers} which already use `N` for a comptime-inferred
size rather than `X`.
Also adds a behavioral test to assert that a string literal is returned.
This was already the case, but the documentation failed to point out
that the returned value is of type `*const [N:0]u8`, i.e. that of a
string literal.
Also adds a behavioral test to assert that this is the case.
Conflicts:
* doc/langref.html.in
* lib/std/enums.zig
* lib/std/fmt.zig
* lib/std/hash/auto_hash.zig
* lib/std/math.zig
* lib/std/mem.zig
* lib/std/meta.zig
* test/behavior/alignof.zig
* test/behavior/bitcast.zig
* test/behavior/bugs/1421.zig
* test/behavior/cast.zig
* test/behavior/ptrcast.zig
* test/behavior/type_info.zig
* test/behavior/vector.zig
Master branch added `try` to a bunch of testing function calls, and some
lines also had changed how to refer to the native architecture and other
`@import("builtin")` stuff.
