- extattr_namespace_to_string()
 - extattr_string_to_namespace()

These are used by the flock wrapper in rustc_data_structures. The
constants were already present in x86_64-linux-gnu and BSD (since
4928bd98).

Also, alphabetize this section, since I'm merging two sections anyway.

Fixes #1113

DragonflyBSD does define 3 of these 14 functions.  But I elected not to
add it to the PR because I can't find any evidence that these syscalls
are used on Dragonfly, even in the base system.  And by themselves,
those three are insufficient for the xattr crate.

Also while here: fix powerpc64, mips, and mips64 pthread types.  These
targets are not yet fully/correctly implemented in rust-libc however.

Last commit fixed the function definition but not the constants.  Oops.

* Added ptrace and constants for all freebsdlike and netbsdlike OSs

Provide a symbol for the `ftok` function declared in sys/ipc.h, for completeness and to allow calling `ftok` to generate the key value for `shmat`.

For range-based locking POSIX fcntl locks are needed. This adds the
constants F_RDLCK, F_UNLCK, and F_WRLCK for FreeBSD, NetBSD, OpenBSD,
DragonFlyBSD, and macOS/iOS. Fortunately these values are defined the same across these platforms.

These are necessary for large file support on 32-bit platforms,
following the same pattern as 74825222 ("Add bindings for
-D_FILE_OFFSET_BITS=64").

Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>