Kernel: Remove sys$select() syscall

Now that the userland has a compatiblity wrapper for select(), the
kernel doesn't need to implement this syscall natively. The poll()
interface been around since 1987, any code still using select()
should be slapped silly.

Note: the SerenityOS source tree mostly uses select() and not poll()
despite SerenityOS having support for poll() since early 2019...

Kernel/API/Syscall.h

@@ -150,7 +150,6 @@ enum class NeedsBigProcessLock {
     S(rmdir, NeedsBigProcessLock::Yes)                      \
     S(sched_getparam, NeedsBigProcessLock::Yes)             \
     S(sched_setparam, NeedsBigProcessLock::Yes)             \
-    S(select, NeedsBigProcessLock::Yes)                     \
     S(sendfd, NeedsBigProcessLock::Yes)                     \
     S(sendmsg, NeedsBigProcessLock::Yes)                    \
     S(set_coredump_metadata, NeedsBigProcessLock::Yes)      \
@@ -264,15 +263,6 @@ struct SC_open_params {
     u16 mode;
 };
 
-struct SC_select_params {
-    int nfds;
-    fd_set* readfds;
-    fd_set* writefds;
-    fd_set* exceptfds;
-    const struct timespec* timeout;
-    const u32* sigmask;
-};
-
 struct SC_poll_params {
     struct pollfd* fds;
     unsigned nfds;

Kernel/CMakeLists.txt

@@ -241,7 +241,6 @@ set(KERNEL_SOURCES
     Syscalls/rename.cpp
     Syscalls/rmdir.cpp
     Syscalls/sched.cpp
-    Syscalls/select.cpp
     Syscalls/sendfd.cpp
     Syscalls/setpgid.cpp
     Syscalls/setuid.cpp

Kernel/Process.h

@@ -315,7 +315,6 @@ class Process final
     ErrorOr<FlatPtr> sys$msyscall(Userspace<void*>);
     ErrorOr<FlatPtr> sys$msync(Userspace<void*>, size_t, int flags);
     ErrorOr<FlatPtr> sys$purge(int mode);
-    ErrorOr<FlatPtr> sys$select(Userspace<const Syscall::SC_select_params*>);
     ErrorOr<FlatPtr> sys$poll(Userspace<const Syscall::SC_poll_params*>);
     ErrorOr<FlatPtr> sys$get_dir_entries(int fd, Userspace<void*>, size_t);
     ErrorOr<FlatPtr> sys$getcwd(Userspace<char*>, size_t);