Fix the yjit-bindgen job

`YJIT_BINDGEN_DIFF_OPTS=--exit-code make yjit-bindgen` is not the same
as `make yjit-bindgen YJIT_BINDGEN_DIFF_OPTS=--exit-code`, of course.

.github/workflows/yjit-ubuntu.yml

@@ -157,7 +157,7 @@ jobs:
         run: ./miniruby --yjit -v | grep "+YJIT"
 
       - name: make ${{ matrix.test_task }}
-        run: make -s -j ${{ matrix.test_task }} RUN_OPTS="$RUN_OPTS" YJIT_BENCH_OPTS="$YJIT_BENCH_OPTS"
+        run: make -s -j ${{ matrix.test_task }} RUN_OPTS="$RUN_OPTS" YJIT_BENCH_OPTS="$YJIT_BENCH_OPTS" YJIT_BINDGEN_DIFF_OPTS="$YJIT_BINDGEN_DIFF_OPTS"
         timeout-minutes: 60
         env:
           RUBY_TESTOPTS: '-q --tty=no'