Cygwin: fcntl.h: Define O_TMPFILE and implement it

Difference to Linux: We can't create files which don't show up
in the filesystem due to OS restrictions.  As a kludge, make a
(half-hearted) attempt to hide the file in the filesystem.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

newlib/libc/include/sys/_default_fcntl.h

@@ -52,6 +52,7 @@ extern "C" {
 #define _FNOFOLLOW      0x100000
 #define _FDIRECTORY     0x200000
 #define _FEXECSRCH      0x400000
+#define _FTMPFILE       0x800000
 
 #define O_BINARY	_FBINARY
 #define O_TEXT		_FTEXT
@@ -63,6 +64,7 @@ extern "C" {
 #define O_DIRECTORY     _FDIRECTORY
 #define O_EXEC          _FEXECSRCH
 #define O_SEARCH        _FEXECSRCH
+#define O_TMPFILE	_FTMPFILE
 #endif
 
 #if __MISC_VISIBLE