apply fix for XHTML1 formating from Nick Wellnhofer fixes bug #141266

* xmlsave.c: apply fix for XHTML1 formating from Nick Wellnhofer
  fixes bug #141266
* test/xhtmlcomp result//xhtmlcomp*: added the specific regression
  test
Daniel
diff --git a/test/xhtmlcomp b/test/xhtmlcomp
new file mode 100644
index 0000000..47dd2a7
--- /dev/null
+++ b/test/xhtmlcomp
@@ -0,0 +1,8 @@
+<?xml version="1.0"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html>
+  <body>
+    <h1><abbr>a</abbr> b</h1>
+  </body>
+</html>