Fix nested references to 'ref' foreach variables. These "walk around" the array being iterated over, so they're a bit trickier than other variables to get right.

module mainargs1;

extern(C) int printf(char*,...);

void main(char[][] args)
{
    foreach(v; args)
    {
        printf("%.*s\n", v.length, v.ptr);
    }
}