internal: add poll() method

Add the poll() method to the internal syscall interface.

Change-Id: I6bf8b59e582214c7e607a8041a9573ef24dd5493
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/internal/sys.cpp b/internal/sys.cpp
index 7e765a9..f6a686e 100644
--- a/internal/sys.cpp
+++ b/internal/sys.cpp
@@ -55,6 +55,11 @@
     return ::ioctl(fd, request, param);
 }
 
+int SysImpl::poll(struct pollfd* fds, nfds_t nfds, int timeout) const
+{
+    return ::poll(fds, nfds, timeout);
+}
+
 SysImpl sys_impl;
 
 } // namespace internal