Describe the issue
A clean build and test fails the new test from #1515:

The following tests FAILED:
	  1 - tsc_test (Failed)

That test's log has a bunch of lines of the form:

00:00:00.000008 debug [tsc.c:71] [_frequency_via_cpuid0x15] cpuid 0x15 didn't give core frequency
00:00:00.000167 debug [tsc.c:142] [_frequency_via_brand_string] Calculated 2500000000 cyclesPerSecond via brand string

plus the following unique lines:

not ok 1 /tsc/rdtscIsCloseToNative
not ok 2 /tsc/rdtscpIsCloseToNative
ok 3 /tsc/emulateRdtscGivesExpectedCycles
ok 4 /tsc/emulateRdtscpGivesExpectedCycles

To Reproduce
Just a clean build and a test, presumably with particular hardware.

Operating System (please complete the following information):

• OS and version: post the output of lsb_release -d
  Ubuntu 21.04
• Kernel version: post the output of uname -a
Linux 5.11.0-22-generic #23-Ubuntu SMP Thu Jun 17 00:34:23 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Shadow (please complete the following information):

• Version: post the output of shadow --version
  Shadow 2.0.0-pre.2
  (shadow --version doesn't seem to include the build info any more, the commit is 277c263)
• Which plug-ins you are using:
  None.

Additional context
Presumably the CPU is relevant here:
Intel(R) Core(TM) i7-6500U

That's not the latest and greatest, but it's certainly newer than what most the computing facilities on campus are providing, where actual experiments would be run, though I haven't tested any of them (I could book some time to try it, if need be).