Remove BuildRoot definition

None of currently supported distributions need that.
It was needed last for EL5 which is EOL now

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

perl-Net-SNMP.spec

@@ -7,7 +7,6 @@ Group:          Development/Libraries
 License:        GPL+ or Artistic
 URL:            http://search.cpan.org/dist/Net-SNMP/
 Source0:        http://search.cpan.org/CPAN/authors/id/D/DT/DTOWN/Net-SNMP-v%{version}.tar.gz
-BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 
 BuildArch:      noarch
 BuildRequires:  coreutils