fix: remove redefinition of `timespec`

They are in the same package, so it's accessible anyway.

core/sys/unix/syscalls_linux.odin

@@ -2077,11 +2077,6 @@ sys_fcntl :: proc "contextless" (fd: int, cmd: int, arg: int) -> int {
 sys_poll :: proc "contextless" (fds: rawptr, nfds: uint, timeout: int) -> int {
 	// NOTE: specialcased here because `arm64` does not have `poll`
 	when ODIN_ARCH == .arm64 {
-		// redefined because we can't depend on the `unix` module here
-		timespec :: struct {
-			tv_sec: i64,
-			tv_nsec: i64,
-		}
 		seconds := i64(timeout / 1_000)
 		nanoseconds := i64((timeout % 1000) * 1_000_000)
 		timeout_spec := timespec{seconds, nanoseconds}