Allow defining a CUSTOM_RELEASE at RPM build time
diff --git a/libxml.spec.in b/libxml.spec.in
index 919969f..8f9f941 100644
--- a/libxml.spec.in
+++ b/libxml.spec.in
@@ -1,6 +1,7 @@
 # Note that this is NOT a relocatable package
 %define ver      @VERSION@
-%define rel      SNAP
+%define  RELEASE SNAP
+%define  rel     %{?CUSTOM_RELEASE} %{!?CUSTOM_RELEASE:%RELEASE}
 %define prefix   /usr
 
 Summary: libXML library