Merged in rnouse/nuttx (pull request #20)

Compilation warning fixup

fs/vfs/fs_poll.c

@@ -49,6 +49,7 @@
 #include <nuttx/clock.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/net/net.h>
+#include <nuttx/semaphore.h>
 
 #include <arch/irq.h>
 
@@ -326,8 +327,6 @@ int file_poll(int fd, FAR struct pollfd *fds, bool setup)
 
 int poll(FAR struct pollfd *fds, nfds_t nfds, int timeout)
 {
-  struct timespec abstime;
-  irqstate_t flags;
   sem_t sem;
   int count = 0;
   int ret;

net/tcp/tcp_appsend.c

@@ -172,7 +172,7 @@ void tcp_appsend(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
   else
     {
 #ifdef CONFIG_NET_TCP_WRITE_BUFFERS
-      DEBUGASSERT(dev->d_sndlen >= 0 && dev->d_sndlen <= conn->mss);
+      DEBUGASSERT(dev->d_sndlen <= conn->mss);
 #else
       /* If d_sndlen > 0, the application has data to be sent. */