replace cjson with json-c

* call json_object_object_foreach from inside own block
  Otherwise it fails with:
  In file included from sysroots/qemux86/usr/include/cjson/linkhash.h:16:0,
                   from sysroots/qemux86/usr/include/cjson/json.h:22,
                   from ../git/Src/base/settings/LocalePreferences.cpp:27:
  ../git/Src/base/settings/LocalePreferences.cpp:593:5: error:   crosses
    initialization of 'lh_entry* entry_nextkeyName'
       json_object_object_foreach(localesObj, keyName, valueName) {
       ^
  ../git/Src/base/settings/LocalePreferences.cpp:645:1: warning: jump to
    label 'Done' [-fpermissive]
   Done:
   ^
  ../git/Src/base/settings/LocalePreferences.cpp:584:14: warning:   from
    here [-fpermissive]
           goto Done;
                ^

Change-Id: Icb17d23a6d1c5b580c1b2a6bc735787ba537badc
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>