Secret macros are cleared on the inherited host prototype when any macro in the parent host prototype is changed

Steps to reproduce:

1. create a template with a discovery rule and a host prototype with secret macro(s)
2. link this template to a host
3. make sure the secret macros are correctly added to the host prototype

   select * from hostmacro where hostid=<hostid> 

4. add one more macro to the template

Result:
Secret macros are cleared on the inherited host prototype