[gfortran,patch] Don't call library function for string copying, take 2

[Jack Howarth]

FX,
    I have tested your proposed patch on a dual G5 running MacOS X 10.4.7
using yesterday's gcc trunk. The patch seems to work okay but I can only
measure a ~13% speed improvement on the pb05 aeromod benchmark (compiled
with -O3). Exactly how much of an improvement do you see on i686?
                  Jack