[libc] Add RT_USING_POSIX macro.

1. Add macro check in rtdebug.h;
2. Use RT_USING_POSIX for poll/select, stdin etc.
3. Split dfs_posix.h to dfs_posix.h, dfs_poll.h and dfs_select.h;

components/libc/KConfig

@@ -1,4 +1,4 @@
-menu "libc"
+menu "POSIX layer and C standard library"
 
 config RT_USING_LIBC
     bool "Enable libc APIs from toolchain"
@@ -9,12 +9,13 @@ config RT_USING_PTHREADS
     default n
 
 if RT_USING_LIBC
-    config RT_USING_POSIX_STDIN
-        bool "Enable stdin"
+    config RT_USING_POSIX
+        bool "Enable POSIX layer for poll/select, stdin etc"
         select RT_USING_DFS
         select RT_USING_DFS_DEVFS
         default y
 
+    if RT_USING_POSIX
     config RT_USING_POSIX_MMAP
         bool "Enable mmap() api"
         default n
@@ -22,6 +23,7 @@ if RT_USING_LIBC
     config RT_USING_POSIX_TERMIOS
         bool "Enable termios feature"
         default n
+    endif
 endif
 
 endmenu

components/libc/compilers/armlibc/stubs.c

@@ -153,7 +153,7 @@ int _sys_read(FILEHANDLE fh, unsigned char *buf, unsigned len, int mode)
 
     if (fh == STDIN)
     {
-#ifdef RT_USING_POSIX_STDIN
+#ifdef RT_USING_POSIX
         size = libc_stdio_read(buf, len);
         return len - size;
 #else
@@ -192,7 +192,7 @@ int _sys_write(FILEHANDLE fh, const unsigned char *buf, unsigned len, int mode)
 #ifndef RT_USING_CONSOLE
         return 0;
 #else
-#ifdef RT_USING_POSIX_STDIN
+#ifdef RT_USING_POSIX
         size = libc_stdio_write(buf, len);
         return len - size;
 #else
@@ -319,7 +319,7 @@ int fgetc(FILE *f)
 {
     char ch;
 
-#ifdef RT_USING_POSIX_STDIN
+#ifdef RT_USING_POSIX
     if (libc_stdio_read(&ch, 1) == 1)
         return ch;
 #endif

components/libc/compilers/dlib/syscall_read.c

@@ -38,7 +38,7 @@ size_t __read(int handle, unsigned char *buf, size_t len)
 
     if (handle == _LLIO_STDIN)
     {
-#ifdef RT_USING_POSIX_STDIN
+#ifdef RT_USING_POSIX
         return libc_stdio_read(buf, len);
 #else
         return _LLIO_ERROR;

components/libc/compilers/dlib/syscall_write.c

@@ -43,7 +43,7 @@ size_t __write(int handle, const unsigned char *buf, size_t len)
         return _LLIO_ERROR;
 #else
 
-#ifdef RT_USING_POSIX_STDIN
+#ifdef RT_USING_POSIX
         return libc_stdio_write((void*)buf, len);
 #else
         rt_device_t console_device;

components/libc/compilers/newlib/libc.c

@@ -43,7 +43,7 @@ int libc_system_init(void)
     dev_console = rt_console_get_device();
     if (dev_console)
     {
-    #if defined(RT_USING_DFS_DEVFS) && defined(RT_USING_POSIX_STDIN)
+    #if defined(RT_USING_POSIX)
         libc_stdio_set_console(dev_console->parent.name, O_RDWR);
     #else
         libc_stdio_set_console(dev_console->parent.name, O_WRONLY);