r156228 breaks rewriting of DeclStmt

Hi @clang,

as said above, a group of var decls is no longer rewritten properly:

// before r156228
int x,y,z;

// introducing r156228
int x,;

This comes from the fact, that TypePrinter::print exits, before the PlaceHolder is printed. I hesitate to provide a simple patch, since I'm unsure how things like

int *x, *y, *z;

can be rewritten correctly. Someone have to look into it.

Best regards
Olaf Krzikalla