Made AST_LIST_REMOVE() simpler and use better names.

* Update doxygen of AST_LIST_REMOVE().
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Merged revisions 376627 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 376628 from http://svn.asterisk.org/svn/asterisk/branches/10
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Merged revisions 376629 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@376630 65c4cc65-6c06-0410-ace0-fbb531ad65f3