Improve compatibility with new CMake macro

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

kactivitymanagerd.spec

@@ -1,3 +1,5 @@
+%undefine __cmake_in_source_build
+
 Name:           kactivitymanagerd
 Summary:        Plasma service to manage user's activities
 Version: 5.19.3
@@ -53,16 +55,12 @@ Provides:       kactivities = %{version}-%{release}
 
 
 %build
-mkdir %{_target_platform}
+%{cmake_kf5}
-pushd %{_target_platform}
+%cmake_build
-%{cmake_kf5} ..
-popd
-
-make %{?_smp_mflags} -C %{_target_platform}
 
 
 %install
-make install/fast DESTDIR=%{buildroot} -C %{_target_platform}
+%cmake_install
 
 %find_lang kactivities5 --with-qt