Stub out poll() syscall and LibC wrapper.

LibC/Makefile

@@ -43,6 +43,7 @@ LIBC_OBJS = \
        utime.o \
        gui.o \
        sys/select.o \
+       poll.o \
        entry.o
 
 OBJS = $(AK_OBJS) $(WIDGETS_OBJS) $(LIBC_OBJS) $(SHAREDGRAPHICS_OBJS)

LibC/poll.cpp

@@ -0,0 +1,14 @@
+#include <poll.h>
+#include <Kernel/Syscall.h>
+#include <errno.h>
+
+extern "C" {
+
+int poll(struct pollfd* fds, int nfds, int timeout)
+{
+    int rc = syscall(SC_poll, fds, nfds, timeout);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
+}
+

LibC/poll.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define POLLIN   (1u << 0)
+#define POLLPRI  (1u << 2)
+#define POLLOUT  (1u << 3)
+#define POLLERR  (1u << 4)
+#define POLLHUP  (1u << 5)
+#define POLLNVAL (1u << 6)
+
+struct pollfd {
+    int   fd;
+    short events;
+    short revents;
+};
+
+int poll(struct pollfd* fds, int nfds, int timeout);
+
+__END_DECLS
+