Kernel/LibC: Implement simple futex

userspace/libraries/LibC/sys/futex.cpp

@@ -0,0 +1,12 @@
+#include <errno.h>
+#include <sys/futex.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+int futex(int op, const uint32_t* addr, uint32_t value, const struct timespec* abstime)
+{
+	errno = 0;
+	while (syscall(SYS_FUTEX, op, addr, value, abstime) == -1 && errno == EINTR)
+		errno = 0;
+	return errno;
+}