spec: Fix building with new cmake macros

= changelog =
resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1863433

Signed-off-by: Nicola Sella <nsella@redhat.com>

dnf-plugins-core.spec

@@ -6,6 +6,8 @@
 %global yum_utils_subpackage_name yum-utils
 %endif
 
+%define __cmake_in_source_build 1
+
 %if 0%{?rhel} && 0%{?rhel} <= 7
 %bcond_with python3
 %else
@@ -32,7 +34,7 @@
 
 Name:           dnf-plugins-core
 Version:        4.0.16
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        Core Plugins for DNF
 License:        GPLv2+
 URL:            https://github.com/rpm-software-management/dnf-plugins-core
@@ -742,6 +744,9 @@ PYTHONPATH=./plugins nosetests-%{python3_version} -s tests/
 %endif
 
 %changelog
+* Mon Aug 10 2020 Nicola Sella <nsella@redhat.com> - 4.0.16-4
+- spec: Fix building with new cmake macros
+
 * Sat Aug 01 2020 Fedora Release Engineering <releng@fedoraproject.org> - 4.0.16-3
 - Second attempt - Rebuilt for
   https://fedoraproject.org/wiki/Fedora_33_Mass_Rebuild