Limit YJIT stats to the measured benchmark code

[rwstauner]

Reset stats at the beginning of the benchmark
and collect stats before loading any additional code.

You can see a difference with the invalidation count:

before:

$  MIN_BENCH_ITRS=1 WARMUP_ITRS=1 MIN_BENCH_TIME=0 RBENV_VERSION=ruby-master YJIT_BENCH_STATS=invalidation_count ruby --yjit-stats=quiet benchmarks/sequel/benchmark.rb
ruby 3.4.0dev (2024-12-04T21:34:16Z master 1c4dbb133e) +YJIT stats +PRISM [arm64-darwin23]
Command: bundle check 2> /dev/null || bundle install
The Gemfile's dependencies are satisfied
itr:   time invalidation_count
 #1:   31ms                  0
 #2:   30ms                  0
invalidation_count:         68

after:

$  MIN_BENCH_ITRS=1 WARMUP_ITRS=1 MIN_BENCH_TIME=0 RBENV_VERSION=ruby-master YJIT_BENCH_STATS=invalidation_count ruby --yjit-stats=quiet benchmarks/sequel/benchmark.rb
ruby 3.4.0dev (2024-12-04T21:34:16Z master 1c4dbb133e) +YJIT stats +PRISM [arm64-darwin23]
Command: bundle check 2> /dev/null || bundle install
The Gemfile's dependencies are satisfied
itr:   time invalidation_count
 #1:   31ms                  0
 #2:   30ms                  0
invalidation_count:          0

[maximecb]

@rwstauner for some reason the test is failing right at the end:

Building native extensions. This could take a while...
/opt/hostedtoolcache/Ruby/3.3.6/x64/lib/ruby/3.3.0/rubygems/ext/builder.rb:125:in `run': ERROR: Failed to build gem native extension. (Gem::Ext::BuildError)

Not immediately clear which gem is failing to build and why this happens so late in the process 🤔

EDIT: seeing that it happens with the --graph option. Guess it's an image library that's failing? If so, typical...

[rwstauner]

The test started failing because the GitHub runner upgraded:
#353