REF_DEBUG: Install refcounter.py to $(ASTDATADIR)/scripts

This change ensures refcounter.py is installed to a place where it
can be found by the Asterisk testsuite if REF_DEBUG is enabled.

ASTERISK-24432 #close
Reported by: Corey Farrell
Review: https://reviewboard.asterisk.org/r/4094/
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Merged revisions 426830 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 426831 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 426832 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 426833 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@426834 f38db490-d61c-443f-a65b-d21fe96a405b