Don't assume per-user groups in test-suite

The tests from commits f2d3be2a87 and
c815822c8b assume per-user groups,
but this is not a generally valid assumption and causes unnecessary
bogus failures in the test-suite in some setups (eg mock)

tests/data/SPECS/replacetest.spec

@@ -1,6 +1,7 @@
 %{!?filetype: %global filetype file}
 %{?fixit: %global havepretrans 1}
 %{!?user: %global user root}
+%{!?grp: %global grp root}
 
 Name:		replacetest%{?sub:-%{sub}}
 Version:	%{ver}
@@ -44,5 +45,5 @@ rm -rf $RPM_BUILD_ROOT
 %endif
 
 %files
-%defattr(-,%{user},%{user},-)
+%defattr(-,%{user},%{grp},-)
 /opt/*

tests/rpmreplace.at

@@ -403,6 +403,7 @@ runroot rpmbuild --quiet -bb \
 	--define "filetype datadir" \
 	--define "filedata README1" \
 	--define "user $(id -u -n)" \
+	--define "grp $(id -g -n)" \
           /data/SPECS/replacetest.spec
 
 runroot rpmbuild --quiet -bb \
@@ -410,6 +411,7 @@ runroot rpmbuild --quiet -bb \
 	--define "filetype datadir" \
 	--define "filedata README2" \
 	--define "user $(id -u -n)" \
+	--define "grp $(id -g -n)" \
           /data/SPECS/replacetest.spec
 
 mkdir "${RPMTEST}"/opt/f00f

tests/rpmverify.at

@@ -78,6 +78,7 @@ runroot rpmbuild --quiet -bb \
         --define "filetype datadir" \
         --define "filedata README1" \
         --define "user $(id -u -n)" \
+        --define "grp $(id -g -n)" \
           /data/SPECS/replacetest.spec
 
 runroot rpm -U /build/RPMS/noarch/replacetest-1.0-1.noarch.rpm