[LyX/master] Dont use invalid tag '' in xhtml export

[Kornel Benko]

commit 161cf523631af91a0197aa3f2b321174d2ca6c4c
Author: Kornel Benko <kor...@lyx.org>
Date:   Mon May 30 09:48:06 2016 +0200

    Dont use invalid tag '<pre></pre>' in xhtml export

diff --git a/lib/layouts/jss.layout b/lib/layouts/jss.layout
index 47e3dae..1055043 100644
--- a/lib/layouts/jss.layout
+++ b/lib/layouts/jss.layout
@@ -226,7 +226,7 @@ Style "Code"
          Series                        Bold
          Color                         Green
        EndFont
-       HTMLTag                         <pre></pre>
+       HTMLTag                         pre
        HTMLItem                        p
 End
 
diff --git a/lib/layouts/stdlayouts.inc b/lib/layouts/stdlayouts.inc
index 8be0d24..dbde134 100644
--- a/lib/layouts/stdlayouts.inc
+++ b/lib/layouts/stdlayouts.inc
@@ -91,7 +91,7 @@ Style Verbatim
        Font
          Family              Typewriter
        EndFont
-       HTMLTag               <pre></pre>
+       HTMLTag               pre
        HTMLItem              p
 End