small fix from Bjorn Reese Daniel

* Makefile.am: small fix from Bjorn Reese
Daniel
diff --git a/Makefile.am b/Makefile.am
index 8872341..02640de 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -27,7 +27,7 @@
 		catalog.c globals.c threads.c c14n.c \
 		xmlregexp.c xmlschemas.c xmlschemastypes.c xmlunicode.c \
 		triostr.c trio.c xmlreader.c relaxng.c dict.c SAX2.c \
-		legacy.c walker.c chvalid.c
+		legacy.c xmldwalk.c chvalid.c
 else
 libxml2_la_SOURCES = SAX.c entities.c encoding.c error.c parserInternals.c  \
 		parser.c tree.c hash.c list.c xmlIO.c xmlmemory.c uri.c  \