Fixed an RMA leak.
Richard Manby authored
If a module written in C uses function getenv, buffer space
is allocated in the RMA. This buffer was never freed, leading
to RMA leakage when the module was 'RMKill'ed or 'RMReInit'ed.

Changes

 c.armsys
   added function _terminate_getenv to free the buffer

 c.stdlib
   added flag getenv_finalised to the exit_s structure

   initialised getenv_finalised in function _exit_init

   atexit tests getenv_finalised, calls _terminate_getenv

 s.version
   version string changed to 4.86 (27 Jul 1998)
31ab84f2