Removed the unnecessary check as requested.

Removed an unnecessary check as requested in review

Adding @chandlerc as a reviewer since first entry in CODE_OWNERS for CMake ^^'

formatting was bad and somehow differential didn't show the endif() - added a trailing newline for that

In D79888#2272669, @ldionne wrote:

Is this review still relevant? If not, let's abandon it to clear up the review queue.

In D79888#2034859, @EricWF wrote:

We could lift the two macros that depend on _NEWLIB_VERSION into the headers that use them.
Then we'll avoid the include in config.

In D79888#2034706, @ldionne wrote:

I am slightly concerned that this also introduces a bunch of declarations in __config, which is the most included file of the library. That would also be the first time we include unistd.h in the libc++ headers (as opposed to the sources used to build the dylib). That might not be an issue, but it's something to keep in mind.

Another way would be to include _newlib_version.h if it exists, would that be better? Would then be a newlib specific patch.

Since this include was deleted as "dead code" before, I added a comment why it is not dead

Cannot commit myself

Also fix duplicated check in filesystem/operations.cpp

Do not include unistd.h on _WIN32, re-add __APPLE__ check and change _POSIX_TIMER check to check for > 0

Included unistd.h and removed the check for __APPLE__, since _POSIX_TIMERS should work there, too

In D79305#2017632, @ldionne wrote:

LGTM generally speaking, but is this triggered by a specific failure you ran into? If so, on what configuration? We should have a way to test this change.