MFC r239133 (by jimharris):

MFC r239133 (by jimharris):
During TSC synchronization test, use rdtsc() rather than rdtsc32(), to
protect against 32-bit TSC overflow while the sync test is running.

On dual-socket Xeon E5-2600 (SNB) systems with up to 32 threads, there
is non-trivial chance (2-3%) that TSC synchronization test fails due to
32-bit TSC overflow while the synchronization test is running.

Approved by:	re (delphij)

git-svn-id: svn://svn.freebsd.org/base/stable/9@267077 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f