The pr #1870 introduced safe_f! macro, which made some functions like
WIFEXITED and WEXITSTATUS const and safe on linux_like platform only,
which causes inconsistency when trying to use those functions in crates
compiled across multiple platforms, as using unsafe on those functions
will generate unused_unsafe warning on linux platforms and lack of
unsafe block will fail compilation on non-linux platforms.

To avoid the inconsistency, this commit applies the same macro for all
the same functions on other platforms too.

On Linux, siginfo_t cannot expose these fields directly due to
https://github.com/rust-lang/libc/issues/716 , so expose them as
functions, just like si_addr and si_value.

In order to get alignment correct on both 32-bit and 64-bit
architectures, define an sifields union that includes a pointer field,
to ensure that it has the same alignment as a pointer.

This triggers a warning on a recent nightly, which in turn breaks CI due to
`#![deny(warnings)]` in libc-test/build.rs

adding PATH_MAX

use type c_int for _PARM_NAME_MAX and _PARM_PATH_MAX

defining uintptr_t = usize and intptr_t/ptrdiff_t = isize, and using uintptr_t to define size_t, and intptr_t to define ssize_t.

2. implement Debug for big size array
3. remove code related to epoll
4. use 'pub enum' for _Vx_semaphore

2. change armv7-wrs-vxworks to armv7-wrs-vxworks-eabihf
3. code cleanup

Define the C interface to vxWorks for x86, x86_64, ARM, ARM 64-bit, PowerPC, PowerPC SPE and PowerPC 64-bit.