Excluding files from source diff

[Samuel Tardieu <sam@debian.org>]

I maintain several packages using PRCS[1] and I'd like not to have the 
package.prj and .prcs_aux files (located in the top directory) showing 
up in the diff, since they don't belong to the sources.

Is there anyway to tell dpkg-buildpackage to exclude some files from
the diff?

  Sam

Footnotes: 
[1]  For those who don't know PRCS, it's a CM tool similar to CVS in
     many regards, but I prefer its spirit, see
     http://www.XCF.Berkeley.EDU/~jmacd/prcs.html
-- 
Samuel Tardieu -- sam@debian.org