Cleaning the /src/dist/build/distributions directory before put the archives

[Milamber]

Hello Vladimir,

With the new building process, the generated archives (zip, tgz and sign 
files) are putting into the directory /src/dist/build/distributions/.
Currently, I have already make 2 release process (v5.2 and v5.2.1(rc4)), 
and now the directory have the v5.2 archives files and the (future) 
v5.2.1 archives.

In the old building process, the archives was put into a "./dist/" 
directory, which was cleaning this directory before (ant task "clean" 
into build.xml).

I think it's will be better to clean the distributions directory before 
put the archives to avoid issues?

For example, after the building process for the 5.2.1 I doing a mistake 
when I checked the signing files vs the hashes in the VOTE mail: I 
seeing the v5.2 *.sha512 files instead of the v5.2.1 *.sha512...

Milamber