#176851:Distribution directory delete follows symbolic links and deletes there too

https://netbeans.org/bugzilla/show_bug.cgi?id=176851

Description: When an user creates a symbolic link into the dist  
folder, the symbolic link is resolved during the clean and the content  
on linked folder is deleted.

Impact: User may lose files in the linked folder. On the other side it  
is rare use case.

Risk: Small change in the build-impl.xml clean target affecting only  
delete of dist folder.

Changeset: http://hg.netbeans.org/main/rev/928e51ce13df

Reviewers: Jiri Prox, Jan Lahoda

Thanks for review,
Tomas