Fix few fedora packaging violation
    
    * Package uses either %{buildroot} or $RPM_BUILD_ROOT
      Note: Using both %{buildroot} and $RPM_BUILD_ROOT
      See: http://fedoraproject.org/wiki/Packaging/Guidelines#macros
    
    * Uses parallel make %{?_smp_mflags} macro.
      - parallel make works well with talloc, tevent, tdb and samba
    
    * Spec use %global instead of %define unless justified.
         Note: %define requiring justification: %define talloc_version 2.0.8,
              %define tdb_version 1.3.3, %define tevent_version 0.9.17