Fix condition logic: The setup seems to support a network without sockets. That is not the case.

Squashed commit of the following:

    sched/sched/sched_getsockets.c:  Fix an error in conditional compilation.
    fs/:  Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
    Documentation/:  Remove all references to CONFIG_NSOCKET_DESCRIPTORS == 0
    include/:  Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
    libs/:  Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
    net/:  Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
    sched/:  Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
    syscall/:  Remove all conditional logic based on CONFIG_NSOCKET_DESCRIPTORS == 0
    tools/:  Fixups for CONFIG_NSOCKET_DESCRIPTORS no longer used to disable sockets.

fs/vfs/fs_close.c

@@ -46,7 +46,7 @@
 #include <nuttx/cancelpt.h>
 #include <nuttx/fs/fs.h>
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
 # include <nuttx/net/net.h>
 #endif
 
@@ -94,7 +94,7 @@ int close(int fd)
     {
       /* Close a socket descriptor */
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS + CONFIG_NSOCKET_DESCRIPTORS))
         {
           ret = net_close(fd);

fs/vfs/fs_dup.c

@@ -78,7 +78,7 @@ int dup(int fd)
     {
       /* Not a valid file descriptor.  Did we get a valid socket descriptor? */
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS + CONFIG_NSOCKET_DESCRIPTORS))
         {
           /* Yes.. dup the socket descriptor.  The errno value is not set. */

fs/vfs/fs_dup2.c

@@ -51,7 +51,7 @@
  * performed.
  */
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
 
 /****************************************************************************
  * Public Functions
@@ -111,5 +111,5 @@ int dup2(int fd1, int fd2)
     }
 }
 
-#endif /* CONFIG_NET && CONFIG_NSOCKET_DESCRIPTORS > 0 */
+#endif /* CONFIG_NET */
 

fs/vfs/fs_dupfd2.c

@@ -76,7 +76,7 @@
  *
  ****************************************************************************/
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
 int fs_dupfd2(int fd1, int fd2)
 #else
 int dup2(int fd1, int fd2)

fs/vfs/fs_fcntl.c

@@ -305,7 +305,7 @@ int fcntl(int fd, int cmd, ...)
     {
       /* No... check for operations on a socket descriptor */
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS + CONFIG_NSOCKET_DESCRIPTORS))
         {
           /* Yes.. defer socket descriptor operations to net_vfcntl(). The

fs/vfs/fs_fdopen.c

@@ -163,7 +163,7 @@ FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb)
        * descriptor.
        */
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       ret = net_checksd(fd, oflags);
 #else
       /* No networking... it is just a bad descriptor */

fs/vfs/fs_fstat.c

@@ -147,7 +147,7 @@ int fstat(int fd, FAR struct stat *buf)
 
   if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
     {
-#if CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       /* Let the networking logic handle the fstat() */
 
       ret = net_fstat(fd, buf);

fs/vfs/fs_ioctl.c

@@ -47,7 +47,7 @@
 
 #include <net/if.h>
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
 # include <nuttx/net/net.h>
 #endif
 
@@ -146,7 +146,7 @@ int ioctl(int fd, int req, unsigned long arg)
     {
       /* Perform the socket ioctl */
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS + CONFIG_NSOCKET_DESCRIPTORS))
         {
           ret = netdev_ioctl(fd, req, arg);

fs/vfs/fs_poll.c

@@ -106,7 +106,7 @@ static int poll_fdsetup(int fd, FAR struct pollfd *fds, bool setup)
     {
       /* Perform the socket ioctl */
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS + CONFIG_NSOCKET_DESCRIPTORS))
         {
           return net_poll(fd, fds, setup);

fs/vfs/fs_read.c

@@ -142,7 +142,7 @@ ssize_t nx_read(int fd, FAR void *buf, size_t nbytes)
 
   if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
     {
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET
       /* No.. If networking is enabled, read() is the same as recv() with
        * the flags parameter set to zero.
        */

fs/vfs/fs_sendfile.c

@@ -103,7 +103,7 @@
 
 ssize_t sendfile(int outfd, int infd, off_t *offset, size_t count)
 {
-#if defined(CONFIG_NET_SENDFILE) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET_SENDFILE
   /* Check the destination file descriptor:  Is it a (probable) file
    * descriptor?  Check the source file:  Is it a normal file?
    */

fs/vfs/fs_write.c

@@ -47,7 +47,7 @@
 #include <errno.h>
 #include <assert.h>
 
-#if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET_TCP
 # include <sys/socket.h>
 #endif
 
@@ -149,7 +149,7 @@ ssize_t nx_write(int fd, FAR const void *buf, size_t nbytes)
 
   if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
     {
-#if defined(CONFIG_NET_TCP) && CONFIG_NSOCKET_DESCRIPTORS > 0
+#ifdef CONFIG_NET_TCP
       /* Write to a socket descriptor is equivalent to send with flags == 0. */
 
       ret = nx_send(fd, buf, nbytes, 0);