Allow res_calendar_ews to work not only with libneon-0.29 but also
with 0.30.

ASTERISK-24325 #close
Reported by: Tzafrir Cohen

Review: https://reviewboard.asterisk.org/r/4068/
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Merged revisions 425286 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 425287 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 425288 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 425289 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@425290 65c4cc65-6c06-0410-ace0-fbb531ad65f3