delete previous doc before generating new one. Avoid problem of missing graphs

git-svn-id: http://root.cern.ch/svn/root/trunk@15374 27541ba8-7e3a-0410-8455-c3a389f83636

smatrix/build/doc_Makefile.am

-# @(#)root/mathcore:$Name:  $:$Id: doc_Makefile.am,v 1.1 2005/09/20 13:52:26 brun Exp $
+# @(#)root/mathcore:$Name:  $:$Id: doc_Makefile.am,v 1.1 2005/12/07 18:22:27 moneta Exp $
 # Author: L. Moneta    2005  
 # 
 #
@@ -13,6 +13,6 @@ EXTRA_DIST =					\
 
 docs:
 	if test -d html; then \
-	(cd html; rm -rf *.html *.gif *.css *.dot *.png formula.repository ) \
+	(rm -rf html) \
 	fi
 	doxygen doxyconfig