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

libldb.spec

@@ -8,9 +8,9 @@
 %global with_python3 0
 %endif
 
-%define talloc_version 2.0.8
-%define tdb_version 1.3.3
-%define tevent_version 0.9.17
+%global talloc_version 2.0.8
+%global tdb_version 1.3.3
+%global tevent_version 0.9.17
 
 Name: libldb
 Version: 1.1.29
@@ -156,15 +156,13 @@ PY3_CONFIG_FLAGS=""
            $PY3_CONFIG_FLAGS \
            --with-privatelibdir=%{_libdir}/ldb
 
-# Don't build with multiple processors
-# It breaks due to a threading issue in WAF
-make V=1
+make %{?_smp_mflags} V=1
 doxygen Doxyfile
 
 %install
-make install DESTDIR=%{buildroot}
+make install DESTDIR=$RPM_BUILD_ROOT
 
-rm -f %{buildroot}%{_libdir}/libldb.a
+rm -f $RPM_BUILD_ROOT%{_libdir}/libldb.a
 
 # Shared libraries need to be marked executable for
 # rpmbuild to strip them and include them in debuginfo