libqxp, add update of config.sub

Change-Id: I4999be84c45fa32d0ae6f62f667b2c7470972f49
(cherry picked from commit 90c22bf8)
Signed-off-by: Michael Meeks <michael.meeks@collabora.com>

external/libqxp/UnpackedTarball_libqxp.mk

@@ -13,6 +13,8 @@ $(eval $(call gb_UnpackedTarball_set_tarball,libqxp,$(QXP_TARBALL)))
 
 $(eval $(call gb_UnpackedTarball_set_patchlevel,libqxp,0))
 
+$(eval $(call gb_UnpackedTarball_update_autoconf_configs,libqxp))
+
 ifeq ($(COM_IS_CLANG),TRUE)
 ifneq ($(filter -fsanitize=%,$(CC)),)
 $(eval $(call gb_UnpackedTarball_add_patches,libqxp, \