patch from Adrian Bunk which adds --disable-rebuild-docs to avoid

* configure.in doc/Makefile.am: patch from Adrian Bunk which
  adds --disable-rebuild-docs to avoid rebuilding them
daniel

svn path=/trunk/; revision=3801
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 55c5ef5..72441a5 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -26,7 +26,11 @@
 
 man_MANS = xmllint.1 xmlcatalog.1
 
+if REBUILD_DOCS
 all: web $(top_builddir)/NEWS libxml2.xsa $(man_MANS)
+else
+all:
+endif
 
 api: libxml2-api.xml libxml2-refs.xml $(APIPAGES) $(srcdir)/html/index.html $(WIN32_DIR)/libxml2.def.src ../elfgcchack.h