Fix syscall deprecation warning on macOS >= 10.12

[z-aki]

Fix #185

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[z-aki]

@googlebot I signed it!

[sergiud]

Currently, it is not possible to test these changes as a corresponding Mac OS X Github workflow is missing.

[z-aki]

Err is that failure my fault ? macOS guards shouldn't affect mingw..

[sergiud]

The failure is very likely caused by this branch.

[z-aki]

Okay, so far I was building glog as part of a downstream project.
Will check separately now.

[z-aki]

Okay it was operator precedence. Fixed now.

[sergiud]

Thanks. Could you please rebase onto current master? CI now supports macOS.

[sergiud]

macOS builds still issue a warning, e.g.,

/Users/runner/work/glog/glog/src/raw_logging.cc:140:3: warning: 'syscall' is deprecated: first deprecated in macOS 10.12 - syscall(2) is unsupported; please switch to a supported interface

[sergiud]

Warning still present.

[z-aki]

Shouldn't the glog project be defining MAC_OS_X_VERSION_MAX_ALLOWED since you know which OSes it will be build built on?
If you can't I can just remove the macOS version stuff and make it dependent on OS only.

[sergiud]

The library doesn't care about MAC_OS_X_VERSION_MAX_ALLOWED, hence it does need to be defined.

Can't you just check the presence of pthread_threadid_np in CMake using check_function_exists and use the function if it is available instead of relying on defines?

[z-aki]

nope warning's still there..
It's sometimes useful to clear cache when dealing with cmake variables.
Also, in one of the older attempts, I just set the code to

#if (defined(OS_MACOSX))
    uint64_t tid64;
    pthread_threadid_np(NULL, &tid64);
    pid_t tid = (pid_t)tid64;
...

and it built fine.
The function was introduced in macOS 10.6 so seems safe to use now.

[sergiud]

I have just one minor remark. You can then squash the commits.

[sergiud]

Great. Thanks!