presence: Enable use of JSON instead of YAML

When `--enable-json` is given at configure time, JSON runtime
configuration is used otherwise the default is to use YAML build time
configuration.

Tested:
    JSON used at runtime when `--enable-json` given at configure time
    generated.hpp not created when using JSON
    generated.hpp created by default when using YAML at build time

Change-Id: Ief4392c3e61ebd15e7310ed37fb390bd59b72d69
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
2 files changed