Stream class should use mbed::fdopen() to attach a stream

mbed::fdopen() is provided in mbed_retarget.cpp which will attach a stream to the
given FileHandle. Removing mbed_set_unbuffered_stream() from stream class as it
is defined in mbed_retarget.cpp. Stream class should not decide whether it wants
to detach buffers from c library or not. mbed::fdopen() will do that based upon
isatty() call. So if a FileHandle is not a tty, i.e., is not a device type, c library
buffering will not be turned off. For device type FileHandles, c library buffering
is turned off.

drivers/RawSerial.cpp

@@ -15,8 +15,10 @@
  */
 #include "drivers/RawSerial.h"
 #include "platform/mbed_wait_api.h"
+#include <stdio.h>
 #include <cstdarg>
 
+
 #if DEVICE_SERIAL
 
 #define STRING_STACK_LIMIT    120

drivers/SerialBase.h

@@ -20,7 +20,6 @@
 
 #if defined (DEVICE_SERIAL) || defined(DOXYGEN_ONLY)
 
-#include "Stream.h"
 #include "Callback.h"
 #include "serial_api.h"
 #include "mbed_toolchain.h"

platform/Stream.cpp

@@ -22,9 +22,10 @@ namespace mbed {
 Stream::Stream(const char *name) : FileLike(name), _file(NULL) {
     // No lock needed in constructor
     /* open ourselves */
-    char buf[12]; /* :0x12345678 + null byte */
-    std::sprintf(buf, ":%p", this);
-    _file = std::fopen(buf, "w+");
+    _file = fdopen(this, "w+");
+    // fdopen() will make us buffered because Stream::isatty()
+    // wrongly returns zero which is not being changed for
+    // backward compatibility 
     if (_file) {
         mbed_set_unbuffered_stream(_file);
     } else {

platform/Stream.h

@@ -19,15 +19,16 @@
 #include "platform/platform.h"
 #include "platform/FileLike.h"
 #include "platform/FileHandle.h"
+#include <cstdio>
 #include <cstdarg>
 
 namespace mbed {
 /** \addtogroup platform */
 /** @{*/
 
-extern void mbed_set_unbuffered_stream(FILE *_file);
-extern int mbed_getc(FILE *_file);
-extern char* mbed_gets(char *s, int size, FILE *_file);
+extern void mbed_set_unbuffered_stream(std::FILE *_file);
+extern int mbed_getc(std::FILE *_file);
+extern char* mbed_gets(char *s, int size, std::FILE *_file);
 /** @}*/
 
 /** File stream