Add a CI check for --yjit-call-threshold=1

Mostly copied from mjit.yml. Thank you Kokubun-san!

.github/workflows/yjit.yml

@@ -0,0 +1,63 @@
+name: YJIT first call
+on: [push, pull_request]
+jobs:
+  make:
+    strategy:
+      matrix:
+        test_task: [ "check" ] # to make job names consistent
+      fail-fast: false
+    runs-on: ubuntu-latest
+    env:
+      TESTOPTS: '-q --tty=no'
+      RUN_OPTS: '--disable-gems --yjit-call-threshold=1'
+      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+    steps:
+      - run: mkdir build
+        working-directory:
+      - name: Install libraries
+        run: |
+          set -x
+          sudo apt-get update -q || :
+          sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm-dev bison autoconf ruby
+      - name: git config
+        run: |
+          git config --global advice.detachedHead 0
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@v2
+        with:
+          path: src
+      - name: Fixed world writable dirs
+        run: |
+          chmod -v go-w $HOME $HOME/.config
+          sudo chmod -R go-w /usr/share
+          sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
+      - name: Set ENV
+        run: |
+          echo "JOBS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
+      - run: autoconf
+        working-directory: src
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc
+      - run: make $JOBS incs
+      - run: make $JOBS
+      - run: sudo make $JOBS -s install
+      - run: sudo apt-get install gdb # used by test / test-all failure
+      - name: Run test
+        run: |
+          ulimit -c unlimited
+          make $JOBS -s test RUN_OPTS="$RUN_OPTS"
+        timeout-minutes: 60
+      - name: Run test-all
+        run: |
+          ulimit -c unlimited
+          make $JOBS -s test-all RUN_OPTS="$RUN_OPTS"
+        timeout-minutes: 60
+      - name: Run test-spec
+        run: |
+          ulimit -c unlimited
+          make $JOBS -s test-spec RUN_OPTS="$RUN_OPTS"
+        timeout-minutes: 60
+
+defaults:
+  run:
+    working-directory: build