Implementing new intrinsic

[FX Coudert]

> The 2nd argument to type_check() is the number of the argument.
> path1 = 0, path2 = 1.

Thanks for this info.

> From a quick glance, the rest looks okay to me.
> I assume you have tested your patch.

At runtime, I get an undefined reference to `_gfortran_rename_i4_sub', 
and libgfortran/intrinsics/rename.c has not been compiled. Is there a 
magic option in the make system I didn't use? (I only used ./configure 
--enable-languages=c,f95 && make).

-- 
FX