[Axis2] Same source file compiled multiple times in the build

[Samisa Abeysinghe]

It looks to me that the same source file is compiled more than once  in 
some cases when I do a full build.
This must be the reason for the *very* slow build time.
To verify this do a 'make clean' and then 'sh build.sh > out'
Then 'vi out' and '/http_worker.c' and search next. There are multiple 
occurences.

This we have to fix. It is annyoing to wait till a build finishes - 
takes *so long* :-(

Samisa...