Merge branch 'tor-github/pr/1322'

  o Minor features (maintenance scripts):

    - Add a coccinelle script to detect bugs caused by incrementing or

      decrementing a variable inside a call to log_debug().  Since

      log_debug() is a macro whose arguments are conditionally evaluated, it

      is usually an error to do this. One such bug was 30628, in which SENDME

      cells were miscounted by a decrement operator inside a log_debug()

      call.  Closes ticket 30743.

// Look for use of expressions with side-effects inside of debug logs.

//

// This script detects expressions like ++E, --E, E++, and E-- inside of

// calls to log_debug().

//

// The log_debug() macro exits early if debug logging is not enabled,

// potentially causing problems if its arguments have side-effects.

@@

expression E;

@@

*log_debug(... , <+...  --E ...+>, ... );

@@

expression E;

@@

*log_debug(... , <+...  ++E ...+>, ... );

@@

expression E;

@@

*log_debug(... , <+...  E-- ...+>, ... );

@@

expression E;

@@

*log_debug(... , <+...  E++ ...+>, ... );