proper handling of the return code for the ps-format (fixes a bug)

--- a/lib/Tools/latex	Sun May 18 15:28:21 2008 +0200
+++ b/lib/Tools/latex	Sun May 18 16:19:48 2008 +0200
@@ -111,7 +111,7 @@
   ps)
     check_root && \
     run_latex && \
-    run_dvips &&
+    run_dvips
     RC="$?"
     ;;
   ps.gz)