package/bind: fix python build

A check for python-ply has been added as this is a dependency of the
dnssec-keymgr script so install host-python-ply to avoid a build failure
if python-ply is not installed on host

Fixes:
 - http://autobuild.buildroot.org/results/96815b1300547c976443bf74b762febdfcc8d3ba

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/bind/bind.mk

@@ -70,8 +70,11 @@ else
 BIND_CONF_OPTS += --with-openssl=no
 endif
 
-# Used by dnssec-checkds and dnssec-coverage
-ifeq ($(BR2_PACKAGE_PYTHON)$(BR2_PACKAGE_PYTHON3),)
+# Used by dnssec-keymgr
+ifeq ($(BR2_PACKAGE_PYTHON_PLY),y)
+BIND_DEPENDENCIES += host-python-ply
+BIND_CONF_OPTS += --with-python=$(HOST_DIR)/usr/bin/python
+else
 BIND_CONF_OPTS += --with-python=no
 endif