aliases without a _DECL?

[Jason Merrill]

To fix PR 12909 with minimal ABI breakage, I'd like to be able to just 
hang extra symbols off the cgraph node for a variable or function and 
have them all emitted together.  I could do this with the existing alias 
mechanisms, but they involve additional DECLs for the aliases.  Does it 
seem reasonable to add extra symbol names to cgraph, or should I make 
dummy DECLs for them?

Jason