Makefile.autotools.in: quiet configure on silent (-s) builds

Use --quiet configure argument when make is invoked with the -s (silent)
option.

package/Makefile.autotools.in

@@ -215,6 +215,7 @@ $(BUILD_DIR)/%/.stamp_configured:
 		--prefix=/usr \
 		--exec-prefix=/usr \
 		--sysconfdir=/etc \
+		$(if $(findstring s,$(MAKEFLAGS)),--quiet,)
 		$($(PKG)_CONF_OPT)
 	$(Q)touch $@