Kernel/LibC: Implement basic epoll

This implementation is on top of inodes instead of fds as linux does it.
If I start finding ports/software that relies on epoll allowing
duplicate inodes, I will do what linux does.

I'm probably missing multiple epoll_notify's which may cause hangs but
the system seems to work fine :dd:

userspace/libraries/LibC/sys/epoll.cpp

@@ -0,0 +1,49 @@
+#include <errno.h>
+#include <unistd.h>
+#include <sys/epoll.h>
+#include <sys/syscall.h>
+
+int epoll_create(int size)
+{
+	if (size <= 0)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+
+	return epoll_create1(0);
+}
+
+int epoll_create1(int flags)
+{
+	return syscall(SYS_EPOLL_CREATE1, flags);
+}
+
+int epoll_ctl(int epfd, int op, int fd, struct epoll_event* event)
+{
+	return syscall(SYS_EPOLL_CTL, epfd, op, fd, event);
+}
+
+int epoll_wait(int epfd, struct epoll_event* events, int maxevents, int timeout)
+{
+	return epoll_pwait(epfd, events, maxevents, timeout, nullptr);
+}
+
+int epoll_pwait(int epfd, struct epoll_event* events, int maxevents, int timeout, const sigset_t* sigmask)
+{
+	timespec ts;
+	timespec* ts_ptr = nullptr;
+	if (timeout >= 0)
+	{
+		ts.tv_sec = static_cast<time_t>(timeout / 1000),
+		ts.tv_nsec = (timeout % 1000) * 1'000'000,
+		ts_ptr = &ts;
+	}
+
+	return epoll_pwait2(epfd, events, maxevents, ts_ptr, sigmask);
+}
+
+int epoll_pwait2(int epfd, struct epoll_event* events, int maxevents, const struct timespec* timeout, const sigset_t* sigmask)
+{
+	return syscall(SYS_EPOLL_PWAIT2, epfd, events, maxevents, timeout, sigmask);
+}