OSR: enable type specialization

[undingen]

           django_template3.py             2.5s (4)             2.5s (4)  +1.0%
                 pyxl_bench.py             2.1s (4)             2.1s (4)  -0.3%
     sqlalchemy_imperative2.py             2.6s (4)             2.6s (4)  -0.3%
                pyxl_bench2.py             1.0s (4)             1.0s (4)  -0.9%
             pyxl_bench_10x.py            16.4s (4)            16.0s (4)  -2.3%
       django_template3_10x.py            11.5s (4)            11.5s (4)  +0.0%
 sqlalchemy_imperative2_10x.py            18.1s (4)            17.6s (4)  -2.8%
            pyxl_bench2_10x.py             8.5s (4)             8.2s (4)  -4.0%
                    interp2.py             2.5s (4)             2.5s (4)  -1.7%
                   raytrace.py             5.6s (4)             5.4s (4)  -3.6%
                      nbody.py             8.0s (4)             7.8s (4)  -3.2%
                   fannkuch.py             6.9s (4)             7.0s (4)  +1.2%
                      fasta.py             3.9s (4)             3.7s (4)  -4.4%
                   pidigits.py             2.6s (4)             2.5s (4)  -1.4%
                   richards.py             0.6s (4)             0.6s (4)  -2.0%
                  deltablue.py             0.9s (4)             0.9s (4)  -1.3%
         sre_compile_ubench.py             0.8s (4)             0.8s (4)  +0.2%
                       geomean                 3.4s                 3.4s  -1.5%