[libc] Implement sys/sysmacros.h Linux header. (#216865)
`<sys/sysmacros.h>` is a Linux header with routines for managing device
number (construct device ID from major/minor IDs) - and contains
functions `major`, `minor`, and `makedev`.
Implement them as simple macro that redirect to the llvm-libc
entrypoints with the same names. This would allow us to have more type
safety (and explicitly specify argument/return types in our entrypoint
implementation), and opens the door for defining those macro in a
different way on other systems, wrapping the invocation of our
implementation with type conversions, if needed (e.g. FreeBSD versions
of these functions use "int" instead of "unsigned int" and are supposed
to be provided by a different header - `<sys/types.h>`).
