Increase maximum logging line length for in-memory log

- Increase the maximum logging line for print done through
  log_output_memory().
  The reason is that we hit this line length when printing some machine
  generated configuration (XML) through the M-plane.  Increase to make
  more of it visible.
- To limit the impact, only increase this locally in function
  log_output_memory(), and statically assert that it will never be
  larger than 64 kB.
  In other places, we use the old limit.
- Move the definition MAX_LOG_TOTAL to log.c, because it's only used
  there.

common/utils/LOG/log.h

@@ -65,12 +65,6 @@
 extern "C" {
 #endif
 
-/** @defgroup _max_length Maximum Length of LOG
- *  @ingroup _macro
- *  @brief the macros that describe the maximum length of LOG
- * @{*/
-
-#define MAX_LOG_TOTAL 16384 /*!< \brief the maximum length of a log */
 /** @}*/
 
 /** @defgroup _log_level Message levels defined by LOG