clang compiler warnings: Remove large chunks of unused code from extconf

This patch fixes a warning caught by clang, in which it detected that large
chunks of extconf were unused. Frankly, I wish we could pretend that all of
extconf was unused, but alas, that is not yet the case.

A few extraneous functions in the parking tests were removed as well, for
the same reason.

Review: https://reviewboard.asterisk.org/r/4553

ASTERISK-24917
Reported by: dkdegroot
patches:
  rb4553.patch submitted by dkdegroot (License 6600)
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Merged revisions 434093 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 434097 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@434099 65c4cc65-6c06-0410-ace0-fbb531ad65f3