posix: sys/stat.h: move O_ACCMODE, RD WRONLY, RDWR to fcntl.h
Previously, `<sys/stat.h>` was declaring the following constants
which should be declared in `<fcntl.h>` according to POSIX.
#define O_CREAT 0x0200
#endif
+#define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
+
+#define O_RDONLY 00
+#define O_WRONLY 01
+#define O_RDWR 02
+
#define O_APPEND 0x0400
#define O_EXCL 0x0800
#define O_NONBLOCK 0x4000
