* tapset/logging.stp (ftrace): New function.
(*): Add kerneldoc to other functions.
* doc/SystemTap_Tapset_Reference/tapsets.tmpl: Process logging.stp.
* stapfuncs.3stap.in: Remove "LOGGING" section, now redundant.
* runtime/autoconf-trace-printk.c: New autoconf test.
* buildrun.cxx (compile_pass): Build it.
* NEWS: Mention it.
* testsuite/buildok/logging.stp: Test it.