Fix MacOS X <12 build issue and the regression from PR1609

[fasterit]

Closes #1611

Thank you to Explorer09 and aestriplex for debugging.

Commit 2e62fae includes some housekeeping:
IOKit is available since MacOS X was born, so remove the guarding. Fix the defines to actually work compiling on MacOS X v11.

[BenBE]

I may be missing something, but AFAICS IOMainPort is used nowhere in the remainder of this file, thus this source/define is unused.

[BenBE]

Based on no visible usage in the file apart from this macro definition or anywhere else inside the Darwin platform code …

$ grep -C3 IOMasterPort -R darwin/
darwin/Platform.c-   const double nanos_per_sec = 1e9;
darwin/Platform.c-   Platform_nanosecondsPerSchedulerTick = nanos_per_sec / scheduler_ticks_per_sec;
darwin/Platform.c-
darwin/Platform.c:   // Since macOS 12.0, IOMasterPort is deprecated and replaced by IOMainPort
darwin/Platform.c-   #if !defined(MAC_OS_VERSION_12_0) || (MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_VERSION_12_0)
darwin/Platform.c:      #define IOMainPort IOMasterPort
darwin/Platform.c-   #endif
darwin/Platform.c-
darwin/Platform.c-   return true;

I propose to apply the following cleanup instead:

Suggested change

	// Since macOS 12.0, IOMasterPort is deprecated and replaced by IOMainPort
	#if !defined(MAC_OS_VERSION_12_0) || (MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_VERSION_12_0)
	#define IOMainPort IOMasterPort
	#endif

Can someone with Darwin please check or point the location this gets used (indirectly)?

[fasterit]

We have
AC_CHECK_DECLS([IOMainPort], [], [], [[#include <IOKit/IOKitLib.h>]])
AC_CHECK_DECLS([IOMasterPort], [], [], [[#include <IOKit/IOKitLib.h>]])
in configure.ac coming from ed7eac5 . I removed the test for iokit_available as that seems to be true for any OS X 10.x and higher. We can probably prune more cruft. Would be good if somebody that actually uses OS X could check.

[fasterit]

Partially committed as 5954fa0

[fasterit]

#1614 is the "full prune" alternative to the remainder of this PR