Make declaration of _TCB idempotent

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4156 42af7a65-404d-4744-a932-0658087f49c3

include/nuttx/fs.h

@@ -379,7 +379,12 @@ EXTERN int close_blockdriver(FAR struct inode *inode);
 /* Used by the OS to clone stdin, stdout, stderr */
 
 #if CONFIG_NFILE_STREAMS > 0
+
+#ifndef __TCB_DEFINED__
 typedef struct _TCB _TCB;
+#define __TCB_DEFINED__
+#endif
+
 EXTERN FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR _TCB *tcb);
 #endif
 

include/nuttx/sched.h

@@ -294,7 +294,15 @@ struct _TCB
 #endif
 
 };
+
+/* Certain other header files may also define this time to avoid circular header
+ * file inclusion issues.
+ */
+
+#ifndef __TCB_DEFINED__
 typedef struct _TCB _TCB;
+#define __TCB_DEFINED__
+#endif
 
 /* This is the callback type used by sched_foreach() */