[GH #837] New comparison benchmark against stress_stringsu.pir
[GH #837] New comparison benchmark against stress_stringsu.pir

Bad news:
There is almost no measurable speed advantage from ascii strings to encoded strings.
With the fix and without the fix, as sprintf handling slows down the test 4x times.

So converting a SREG and const to encoded STRING* will not gain much performance.

youprofit/parrot,FROGGS/parrot,youprofit/parrot,tkob/parrot,parrot/parrot,FROGGS/parrot,youprofit/parrot,youprofit/parrot,tkob/parrot,youprofit/parrot,FROGGS/parrot,parrot/parrot,parrot/parrot,tkob/parrot,youprofit/parrot,parrot/parrot,tkob/parrot,FROGGS/parrot,FROGGS/parrot,youprofit/parrot,FROGGS/parrot,tkob/parrot,tkob/parrot,tkob/parrot,youprofit/parrot,parrot/parrot,tkob/parrot,FROGGS/parrot,FROGGS/parrot