Merge #18229: random: drop unused MACH time headers

d36146009f Drop unused mach time headers (Ben Woosley)

Pull request description:

  Now that we're no longer special-casing clock usage for MacOS (see #17800), we're
  not referencing anything defined in these headers.

  Incidentally, this removes our last reference to the `__MACH__` system def. 🎉

ACKs for top commit:
  jonasschnelli:
    utACK d36146009f
  fanquake:
    ACK d36146009f - thanks.

Tree-SHA512: 246045b0683a705ad034416e8ace2024e652026a6c0517b6797320e52fc18a6e111ec2e405ca40653bd1d6421bb7755232e8fec22651fff8e448eb7d5646a954

src/randomenv.cpp

@@ -38,11 +38,6 @@
 #include <sys/utsname.h>
 #include <unistd.h>
 #endif
-#ifdef __MACH__
-#include <mach/clock.h>
-#include <mach/mach.h>
-#include <mach/mach_time.h>
-#endif
 #if HAVE_DECL_GETIFADDRS
 #include <ifaddrs.h>
 #endif