Ensure global types in the config framework are initialized

Ensure global types in the config framework are initialized

If a config object was allocated but one of its global objects was
never encountered, then the global object's defaults were never
applied. Ensure that global objects are initialized properly upon
allocation instead of on configuration.

Review: https://reviewboard.asterisk.org/r/2866/
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Merged revisions 399564 from http://svn.asterisk.org/svn/asterisk/branches/11

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/12@399565 65c4cc65-6c06-0410-ace0-fbb531ad65f3