Restricting freecontact to 64 bit architectures

Hi,

while my test build on i386 went fine I think its time to more
agressively remove binaries for 32bit architectures for packages where
these are not used in practice.  If you agree I will make freecontact
   Build-Depends: architecture-is-64-bit
and ask for removal of 32 bit architectures which would solve this bug
as well.

I'd be happy if somebody else might beat me in doing so.

Kind regards
    Andreas.