apps/system/lzf:

  - The maximum block size is now configuration setting in order to give finer control over memory usage.
  - The compression/decompression buffers have been moved out the stack and are now global variables.  This eliminates the need to set large stack sizes to use this utility.
  - Added semaphore protection of all global variables for the case of the FLAT or PROTECTED builds.  Unlike the KERNEL build, the same global variables will be used by each instance of the LZF utility.  If you want thread safety, then you must either (a) serialize all access to the global variables, or (b) pack the global variables into a structure and allocate that structure on each execution of lzf_main().