make sure the new header will be included when generating a new

* include/libxml/Makefile.am: make sure the new header will
  be included when generating a new distribution.
Daniel
diff --git a/include/libxml/Makefile.am b/include/libxml/Makefile.am
index ff7f4f3..0dd7e73 100644
--- a/include/libxml/Makefile.am
+++ b/include/libxml/Makefile.am
@@ -41,7 +41,8 @@
 		xmlreader.h \
 		relaxng.h \
 		dict.h \
-		SAX2.h
+		SAX2.h \
+		xmlexports.h
 
 install-exec-hook:
 	$(mkinstalldirs) $(DESTDIR)$(xmlincdir)