Generate config.h

This allows us to remove a lot of #ifdef's. Either we want to use
a config.h or we don't. Since we'll want it for e.g. optional gsound
support later on let's have it.

eek/eek-theme-context.c

@@ -19,9 +19,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifdef HAVE_CONFIG_H
 #include "config.h"
-#endif  /* HAVE_CONFIG_H */
 
 #include "eek-theme.h"
 #include "eek-theme-context.h"