Really fix autoconf-2.60 misery:

Really fix autoconf-2.60 misery:
- don't run autoheader if we don't have config.h (Thanks flameeyes!)
- clean up mess with errors and warnings so we actually see what's
  happening
- make sure we abort mission if autoconfing the bunch fails
- require autoconf 2.60 now, as we changed the configure script to do
  it's dirty voodoo based on the output of 2.60, which is different from
  its predecessor(s)

svn path=/main/branches/prefix/; revision=4936