[libc] Add stub pthread_attr_getschedparam / pthread_attr_setschedparam (#173440)
Add the boilerplate for declaring these POSIX functions and
providing implementations. So far the only implementations are
just stubs that fail with ENOTSUP, and they are neither tested
nor included in any CMake entrypoints lists. More work is still
required to add the actual fields to the pthread_attr_t and
implement the support in the Linux pthread_create et al, but that
is not done here. It's not an especially large amount of work,
but more than just trivial.
The scaffolding here paves the way for that later work, but is
also immediately useful for filling out the subset of POSIX
pthread_attr_* functions that Fuchsia's libc already supports.
GitOrigin-RevId: 10d6a02016270d29fef4ae58101777b149160c7a
6 files changed
