Errors if gperf isn't installed

[David Zeuthen]

On Mon, 2007-06-11 at 16:17 +0100, Richard Hughes wrote:
> > Looks good but we should probably also test for awk... 
> 
> Sure, I think that's already done in the default configure, but I'll
> check it out.

If the answer is that running ./configure will require awk _anyway_ I
guess it's safe to just add AC_PROG_AWK or something (disclaimer: I'm an
autotools n00b). It just needs to be explicit I think.

      David