Fix shadowing warning for identifier symlink

Hi:

I was getting build warnings on gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 on my Ubuntu 12.04 machine because the local variable `symlink` was shadowing `symlink(2)`.

I've fixed this by renaming `symlink` and renaming its related size variable.

FWIW I believe this is fixed with newer versions of gcc, but probably better to just change it to avoid breaking builds with older compilers.