[patch] Change the .ll syntax for comdats and add a syntactic sugar

[Duncan P. N. Exon Smith]

> On 2015-Jan-06, at 13:32, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> 
>>> It keeps it nice and terse when possible and we only need to check if the
>>> next token after comdat is '(' to see if it is in an explicit comdat group.
>> 
>> I like it. I will post a patch with it.
> 
> llvm and clang patches attached. What do you think?

These LGTM.  And the syntax is better after David's suggestion.