[MERGE] Workaround for running `make exe` second time: remove all compiled extensions because they will be recompiled anyway.

[Martin Pool]

Martin Pool has voted approve.
Status is now: Approved
Comment:
I'd like to see a comment in there explaining the purpose of this 
apparently redundant line.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3Cgvmjn4%247au%241%40ger.gmane.org%3E
Project: Bazaar