linux-user: improve target_to_host_sock_type conversion

linux-user: improve target_to_host_sock_type conversion

Previous implementation has failed to take into account different value of
SOCK_NONBLOCK on target and host, and existence of SOCK_CLOEXEC.
The same conversion has to be applied both for do_socket and do_socketpair,
so the code has been isolated in a static inline function.

enum sock_type in linux-user/socket.h has been extended to include
TARGET_SOCK_CLOEXEC and TARGET_SOCK_NONBLOCK, similar to definition in libc.
The patch also includes necessary code style changes (tab to spaces) in the
header file since most of the file has been touched by this change.

Signed-off-by: Petar Jovanovic <petar.jovanovic@imgtec.com>
Message-id: 1372639454-7560-1-git-send-email-petar.jovanovic@rt-rk.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>