Started to add conditional require statements for the various RH-based distributions.

scripts/rpm-data/klayout.spec

@@ -31,6 +31,18 @@ BuildRoot:      %{_tmppath}/%{name}-%{version}-build
 # so's of klayout itself)
 AutoReqProv: 	no
 
+# CentOS7 requirements
+%if "%{target_system}" == "centos7"
+Requires:	ruby >= 2.0.0
+Requires:	python >= 2.7.5
+Requires:       qt >= 4.8.5
+%endif
+
+%if "%{target_system}" == "centos6"
+# CentOS6 requirements
+# ...
+%endif
+
 %description
 Mask layout viewer and editor for the chip design engineer.