bug#18410: Use SAFE_ALLOCA etc. to avoid unbounded stack allocation.

[Paul Eggert]

Dmitry Antipov wrote:
> If __GNUC__, can't we use __attribute__ ((cleanup (freeing_function)))
> for implicit calls
> to SAFE_FREE

We could, but I don't see how this would help.  For non-GNUC we need to 
call the freeing function explicitly anyway, so __attribute__ ((cleanup 
...)) would simply clutter up the source, no?  Or perhaps I'm not 
understanding the suggestion.