Regressions caused by copy_string patch.

[Jack Howarth]

Steve,
   With FX's proposed fix, I get...

gfortran -m64 -O actual_array_substr_2.f90
actual_array_substr_2.f90: In function 'MAIN__':
actual_array_substr_2.f90:10: internal compiler error: in copy_to_mode_reg, at explow.c:635
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.

...on MacOS X.
       Jack