Add --enable-yjit config option, test for success

Author: MSP-Greg

.github/workflows/build.yml

@@ -100,13 +100,15 @@ jobs:
     - run: chmod 755 $HOME # https://github.com/actions/virtual-environments/issues/267
     - run: mkdir -p ~/.rubies
     - run: ./autogen.sh
-    - run: ./configure --prefix=$HOME/.rubies/ruby-${{ matrix.name }} --enable-shared --disable-install-doc
+    - run: ./configure --prefix=$HOME/.rubies/ruby-${{ matrix.name }} --enable-shared --disable-install-doc --enable-yjit
       if: startsWith(matrix.os, 'ubuntu')
-    - run: ./configure --prefix=$HOME/.rubies/ruby-${{ matrix.name }} --enable-shared --disable-install-doc --with-openssl-dir=$(brew --prefix [email protected]) --with-readline-dir=$(brew --prefix readline)
+    - run: ./configure --prefix=$HOME/.rubies/ruby-${{ matrix.name }} --enable-shared --disable-install-doc --enable-yjit --with-openssl-dir=$(brew --prefix [email protected]) --with-readline-dir=$(brew --prefix readline)
       if: startsWith(matrix.os, 'macos')
     - run: make -j4
     - run: make install
 
+    - run: ruby --yjit -e 'exit RubyVM::YJIT.enabled?'
+
     - name: Create archive
       run: tar czf ruby-${{ matrix.name }}-${{ steps.platform.outputs.platform }}.tar.gz -C ~/.rubies ruby-${{ matrix.name }}