runtime: skip TestTimePprof on illumos

On illumos nanotime calls libc, like on the other systems for which
TestTimePprof is skipped.

For #43118

Change-Id: I370d3f098a261185920cb1e3e3402d16200e301a
Reviewed-on: https://go-review.googlesource.com/c/go/+/366737
Trust: Tobias Klauser <[email protected]>
Run-TryBot: Tobias Klauser <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: tklauser

src/runtime/crash_test.go

@@ -717,7 +717,7 @@ func TestTimePprof(t *testing.T) {
 	// This test is unreliable on any system in which nanotime
 	// calls into libc.
 	switch runtime.GOOS {
-	case "aix", "darwin", "openbsd", "solaris":
+	case "aix", "darwin", "illumos", "openbsd", "solaris":
 		t.Skipf("skipping on %s because nanotime calls libc", runtime.GOOS)
 	}