ntp: sync updates from upstream, replace 'examples' use flag with 'perl'

Some minor updates from upstream such as a fix for building without
openssl which doesn't impact our current configuration. Additionally,
our 'examples' use flag was non-functional because 4.2.8 now includes
scripts in its normal build system and installs them to bin. Instead add
a better named 'perl' use flag and patch the build.
Merge pull request #1025 from marineam/ntp

ntp: sync updates from upstream, replace 'examples' use flag with 'perl'