[debug-early] fix problem with template parameter packs

[Aldy Hernandez]

On 05/05/2015 02:08 PM, Jason Merrill wrote:
> On 05/04/2015 09:29 PM, Aldy Hernandez wrote:
>> The code handling parameter DIEs needed a little tweaking for variable
>> length template arguments.  I've relaxed the original assert, but this
>> may require tweaking at branch review time-- hopefully later this week.
>
> What testcase motivated this?  We're within a formal_parameter_pack, but

Pretty much every other test in the libstdc++-v3 testsuite was failing 
with the ICE I elided in my patch.

I wasn't able to narrow it down to a tiny test, but I can do so if you 
want. ??

Aldy