tools/expat: fix docbook2man error on some systems

On some systems (Gentoo) configure stage fails because of docbook2man
working with SGML rather than with XML. We don't need xmlwf man pages so
we disable this.

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

tools/expat/Makefile

@@ -19,6 +19,9 @@ HOST_BUILD_PARALLEL:=1
 
 include $(INCLUDE_DIR)/host-build.mk
 
+HOST_CONFIGURE_ARGS += \
+	--without-docbook
+
 define Host/Install
 	$(MAKE) -C $(HOST_BUILD_DIR) install
 endef