Skip some builtins tests if there is no C99 runtime

[Janis Johnson]

On Wed, 2007-09-19 at 14:17 +0100, Richard Sandiford wrote:
> This patch is part 2/2 of the change described here:
> 
>     http://gcc.gnu.org/ml/gcc-patches/2007-09/msg01539.html

> Tested on x86_64-linux-gnu, where all tests continue to run and pass.
> Also tested on mipsisa64-elfoabi, where the tests are now correctly
> skipped.  OK to install?

OK.

Janis