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

[François-Xavier Coudert]

> You need to bump the .so version of libgfortran if you do this (maybe we
> have done so for 4.2 compared to 4.1.x already).

Yes, I think there is a general agreement that this will be done (at
least before branching). Anyway, the library is already incompatible,
so I'm not adding anything horrible here :)

FX