Revert "configure: add #include "version.h" to config.h"

This reverts commit ca21116b3f53a9bdd74364bfab9cde70a044b165.

Revert suggested by Jamal:
"Bad secondary effect i just noticed: Every time version.h is changed
 (git pull for example), anything that includes config.h will be
 recompiled. And that means pretty much every single file in the tree.
"