Prep for 6.16 release

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@4475 7fd9a85b-ad96-42d3-883c-3090e2eb8679
3 jobs for NuttX-6.16 in 8 seconds (queued for 6 minutes and 16 seconds)
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