Logging: Cleanup of log.c

Logging: Cleanup of log.c

   o  log_progname[] moved to log_init()
   o  Both vmsg() and log_pass_msg() now allocate the buffer on the stack
      if the message is smaller than 256 bytes.
   o  log_pid is used instead of repeated calls to getpid()
   o  sizeof(array) always preferred over repeated constants
   o  Many coding style cleanups to make the old and new code fit together.
   o  Namespace cleanups
   o  Updated comments