also filter label symbols

The bug here is that, with dwz -m, a function (and a label) appear in
both a PU and a CU when running cplabel.exp.  So, a breakpoint gets
two locations:

    (gdb) break foo::bar:to_the_top
    Breakpoint 2 at 0x400503: foo::bar:to_the_top. (2 locations)

What is especially wacky is that both locations are at the same place:

    (gdb) info b
    Num     Type           Disp Enb Address            What
    1       breakpoint     keep y   <MULTIPLE>
    1.1                         y     0x000000000040051c foo::bar:get_out_of_here
    1.2                         y     0x000000000040051c foo::bar:get_out_of_here

This happens due to the weird way we run "dwz -m".
It's unclear to me that this would ever happen for real code.

While I think this borders on "diminishing returns" territory, the fix
is pretty straightforward: use the existing address-filtering function
in linespec to also filter when looking at labels.

Built and regtested (both ways) on x86-64 Fedora 18.

	* linespec.c (convert_linespec_to_sals): Use maybe_add_address
	when adding label symbols.