Fix printing of types in initializers with suppressed tags.

Tag and specifier printing can be suppressed in Decl::printGroup, but these suppressions leak into the initializers. Thus
    int *x = ((void *)0), *y = ((void *)0);
gets printed as
    int *x = ((void *)0), *y = ((*)0);
And
    struct { struct Z z; } z = {(struct Z){}};
gets printed as
    struct { struct Z z; } z = {(){}};
The stops the suppressions from leaking into the initializers.

Patch by Nick Sumner!

Differential Revision: http://reviews.llvm.org/D16438

llvm-svn: 258679