C99 in Bison

[Joel E. Denny]

A couple of years ago, Paul Eggert recommended we wait a couple of years 
at least to start requiring users to have C99 compilers in order to build 
Bison:

  http://lists.gnu.org/archive/html/bison-patches/2007-05/msg00012.html

How about now?  I'd love to be able to do things like:

  void
  foo (int *array, size n)
  {
    int array2[n]; // variable-length array
    for (int i = 0; i < n; ++i) // mixed declarations and code
      {
        // Single-line comments, which are so tempting that we've already 
        // begun using them.  Oops.
      }
  }

If this is ok, we should probably add a configure.ac check for C99.

And what about C99 for building Bison-generated parsers?