Update:

I have just retried to build 4.8.0 for my ce platform using shadow builds and encountered the same issue.
My source directory was c:\qt\4.8.0-master and my target directory was c:\qt\4.8.0(ce_armv4i)

with this set up the syncqt failed to run.

However when i changed my target directory to c:\qt\4.8.0-ce_armv4i i can build the qt libraries

Hope this is of help to anyone having problems with shadow builds.

Robin