Change instrprof LLVM_VP_MAX_NUM_VALS_PER_SITE threshold.

We're having flaky failures on this test on the sanitizer slow
buildbot. Not per-run flaky, but it'll be green for a while, then red
for a while. I suspect that changes in codegen are causing the
LLVM_VP_MAX_NUM_VALS_PER_SITE=150 to be above and below the limit
sporadically. The limit on my machine using lld and a non-bootstrapped
compiler is 175, but the bot uses GNU ld and ld.gold at different
points, which could be affecting behaviour.

Change this threshold to LLVM_VP_MAX_NUM_VALS_PER_SITE=130 in order to
try and get it below the failure point, at least for the foreseeable
future.

http://lab.llvm.org:8011/#/builders/37/builds/2744