Simplify redisplay-x/separate_textual_runs

[Aidan Kehoe]

 Ar an t-aonú lá is triochad de mí Márta, scríobh Stephen J. Turnbull: 

 > Aidan Kehoe writes:
 > 
 >  > My last changes to separate_textual_runs eliminated unnecessary
 >  > assignments during the loop that had been there since the Mule
 >  > merge.
 > 
 > But AIUI, optimization by the compiler will do that for you, too. 

In every case? No, not really. (Okay, I haven’t looked at the generated
assembler for that case.)

 > The resulting code is usually cleaner and more readable, but AFAIK it has
 > no impact on performance in an optimized build. Is that wrong?

-- 
On the quay of the little Black Sea port, where the rescued pair came once
more into contact with civilization, Dobrinton was bitten by a dog which was
assumed to be mad, though it may only have been indiscriminating. (Saki)