linux-user: Add support for SIOC<G|S>IFPFLAGS ioctls for all targets

linux-user: Add support for SIOC<G|S>IFPFLAGS ioctls for all targets

Add support for getting and setting extended private flags of a
network device via SIOCSIFPFLAGS and SIOCGIFPFLAGS ioctls.

The ioctl numeric values are platform-independent and determined by
the file include/uapi/linux/sockios.h in Linux kernel source code:

  #define SIOCSIFPFLAGS 0x8934
  #define SIOCGIFPFLAGS	0x8935

These ioctls get (or set) the field ifr_flags of type short in the
structure ifreq. Such functionality is achieved in QEMU by using
MK_STRUCT() and MK_PTR() macros with an appropriate argument, as
it was done for existing similar cases.

Signed-off-by: Neng Chen <nchen@wavecomp.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <1554839486-3527-1-git-send-email-aleksandar.markovic@rt-rk.com>
Message-Id: <1558282527-22183-4-git-send-email-aleksandar.markovic@rt-rk.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>