Add missing fexecve() - execute program specified via file descriptor.

Reference: http://pubs.opengroup.org/onlinepubs/9699919799/functions/fexecve.html

Add signalfd and related to android

Add missing flags to Linux and Android

Add all current fallocate flags

Also move them to the common Linux module, as they are not platform-specific.
See include/uapi/linux/falloc.h.

Add mac structs

With this one, I'll have almost all the structs I need directly in libc. :)

Restore SYS_* constants to the c_long type

cc https://github.com/rust-lang/libc/pull/672#issuecomment-316406664

glibc support is behind, as indicated by
https://github.com/karelzak/util-linux/blob/master/sys-utils/fallocate.c

Also move them to the common Linux module, as they are not platform-specific.
See include/uapi/linux/falloc.h.

Add syscall table for x86 and x86_64

I'm wondering if we should use `SYS_write` or `__NR_write`. Both are available to C programs.

There were previous definitions of SYS_gettid and SYS_perf_event_open

Enable preadv and pwritev on the BSDs

Redox: Use c_long instead of usize for off_t

Add missing constants for mac

I didn't find these constants on other systems than mac so only mac is updated...

Add execvpe for support *nix platforms

Add missing if_data and if_msghdr structs

Add more termios s390x constants

These are all that remain for nix to compile on s390x.

These are all that remain for nix to compile on s390x

Add CMSPAR to linux/mips

It needs to be skipped during testing because there's no way to include
a combination of headers that will expose it without giving a "type has
already been defined" error.

merge poll constants in BSD platforms

Sorry for the different PR about the same constants, the miss in the different architectures appeared progressively as I modify nix source to expose the poll function for the different platforms.

Hopefully, it should be the last one !

add poll constants to FreeBSD and DragonFly

add poll constants to Android

Adding `POLLRDNORM`, `POLLRDBAND`, `POLLWRBAND` and `POLLWRNORM` for Android